<?xml version="1.0" encoding="utf-8"?>
<!--XBRL document created with Toppan Merrill Bridge  11.3.0.1 -->
<!--Based on XBRL 2.1-->
<!--Created on: 5/8/2026 9:42:25 PM-->
<!--Modified on: 5/8/2026 9:42:25 PM-->
<link:linkbase xmlns="http://www.xbrl.org/2003/linkbase" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xlink="http://www.w3.org/1999/xlink" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrli="http://www.xbrl.org/2003/instance">
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DocumentDocumentAndEntityInformation" roleURI="http://www.hudsontech.com/role/DocumentDocumentAndEntityInformation" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#StatementConsolidatedBalanceSheets" roleURI="http://www.hudsontech.com/role/StatementConsolidatedBalanceSheets" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#StatementConsolidatedBalanceSheetsParenthetical" roleURI="http://www.hudsontech.com/role/StatementConsolidatedBalanceSheetsParenthetical" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#StatementConsolidatedStatementsOfIncome" roleURI="http://www.hudsontech.com/role/StatementConsolidatedStatementsOfIncome" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#StatementConsolidatedStatementsOfStockholdersEquity" roleURI="http://www.hudsontech.com/role/StatementConsolidatedStatementsOfStockholdersEquity" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#StatementConsolidatedStatementsOfCashFlows" roleURI="http://www.hudsontech.com/role/StatementConsolidatedStatementsOfCashFlows" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureSummaryOfSignificantAccountingPolicies" roleURI="http://www.hudsontech.com/role/DisclosureSummaryOfSignificantAccountingPolicies" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureFairValue" roleURI="http://www.hudsontech.com/role/DisclosureFairValue" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureInventories" roleURI="http://www.hudsontech.com/role/DisclosureInventories" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosurePropertyPlantAndEquipment" roleURI="http://www.hudsontech.com/role/DisclosurePropertyPlantAndEquipment" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureLeases" roleURI="http://www.hudsontech.com/role/DisclosureLeases" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureGoodwillAndIntangibleAssets" roleURI="http://www.hudsontech.com/role/DisclosureGoodwillAndIntangibleAssets" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureShareBasedCompensation" roleURI="http://www.hudsontech.com/role/DisclosureShareBasedCompensation" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureShortTermAndLongTermDebt" roleURI="http://www.hudsontech.com/role/DisclosureShortTermAndLongTermDebt" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureAccruedExpensesAndOtherCurrentLiabilities" roleURI="http://www.hudsontech.com/role/DisclosureAccruedExpensesAndOtherCurrentLiabilities" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureAcquisition" roleURI="http://www.hudsontech.com/role/DisclosureAcquisition" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureShareRepurchases" roleURI="http://www.hudsontech.com/role/DisclosureShareRepurchases" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureSegmentInformation" roleURI="http://www.hudsontech.com/role/DisclosureSegmentInformation" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureSummaryOfSignificantAccountingPoliciesPolicies" roleURI="http://www.hudsontech.com/role/DisclosureSummaryOfSignificantAccountingPoliciesPolicies" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureSummaryOfSignificantAccountingPoliciesTables" roleURI="http://www.hudsontech.com/role/DisclosureSummaryOfSignificantAccountingPoliciesTables" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureInventoriesTables" roleURI="http://www.hudsontech.com/role/DisclosureInventoriesTables" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosurePropertyPlantAndEquipmentTables" roleURI="http://www.hudsontech.com/role/DisclosurePropertyPlantAndEquipmentTables" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureLeasesTables" roleURI="http://www.hudsontech.com/role/DisclosureLeasesTables" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureGoodwillAndIntangibleAssetsTables" roleURI="http://www.hudsontech.com/role/DisclosureGoodwillAndIntangibleAssetsTables" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureShareBasedCompensationTables" roleURI="http://www.hudsontech.com/role/DisclosureShareBasedCompensationTables" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureAccruedExpensesAndOtherCurrentLiabilitiesTables" roleURI="http://www.hudsontech.com/role/DisclosureAccruedExpensesAndOtherCurrentLiabilitiesTables" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureAcquisitionTables" roleURI="http://www.hudsontech.com/role/DisclosureAcquisitionTables" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureSegmentInformationTables" roleURI="http://www.hudsontech.com/role/DisclosureSegmentInformationTables" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureSummaryOfSignificantAccountingPoliciesDetails" roleURI="http://www.hudsontech.com/role/DisclosureSummaryOfSignificantAccountingPoliciesDetails" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureSummaryOfSignificantAccountingPoliciesRevenuesDetails" roleURI="http://www.hudsontech.com/role/DisclosureSummaryOfSignificantAccountingPoliciesRevenuesDetails" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureSummaryOfSignificantAccountingPoliciesIncomePerShareDetails" roleURI="http://www.hudsontech.com/role/DisclosureSummaryOfSignificantAccountingPoliciesIncomePerShareDetails" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureInventoriesDetails" roleURI="http://www.hudsontech.com/role/DisclosureInventoriesDetails" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosurePropertyPlantAndEquipmentPropertyPlantAndEquipmentDetails" roleURI="http://www.hudsontech.com/role/DisclosurePropertyPlantAndEquipmentPropertyPlantAndEquipmentDetails" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosurePropertyPlantAndEquipmentAdditionalInformationDetails" roleURI="http://www.hudsontech.com/role/DisclosurePropertyPlantAndEquipmentAdditionalInformationDetails" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureLeasesAdditionalInformationDetails" roleURI="http://www.hudsontech.com/role/DisclosureLeasesAdditionalInformationDetails" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureLeasesMaturityOfLeasePaymentsDetails" roleURI="http://www.hudsontech.com/role/DisclosureLeasesMaturityOfLeasePaymentsDetails" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureLeasesBalanceSheetAndOtherDetails" roleURI="http://www.hudsontech.com/role/DisclosureLeasesBalanceSheetAndOtherDetails" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureLeasesSupplementalCashFlowDetails" roleURI="http://www.hudsontech.com/role/DisclosureLeasesSupplementalCashFlowDetails" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureGoodwillAndIntangibleAssetsAdditionalInformationDetails" roleURI="http://www.hudsontech.com/role/DisclosureGoodwillAndIntangibleAssetsAdditionalInformationDetails" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureGoodwillAndIntangibleAssetsOtherIntangibleAssetsDetails" roleURI="http://www.hudsontech.com/role/DisclosureGoodwillAndIntangibleAssetsOtherIntangibleAssetsDetails" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureShareBasedCompensationDetails" roleURI="http://www.hudsontech.com/role/DisclosureShareBasedCompensationDetails" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureShareBasedCompensationSummaryOfActivityForStockOptionsAndStockAppreciationRightsDetails" roleURI="http://www.hudsontech.com/role/DisclosureShareBasedCompensationSummaryOfActivityForStockOptionsAndStockAppreciationRightsDetails" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureShareBasedCompensationWeightedAverageContractualLifeInYearsAndWeightedAverageExercisePriceDetails" roleURI="http://www.hudsontech.com/role/DisclosureShareBasedCompensationWeightedAverageContractualLifeInYearsAndWeightedAverageExercisePriceDetails" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureShortTermAndLongTermDebtDetails" roleURI="http://www.hudsontech.com/role/DisclosureShortTermAndLongTermDebtDetails" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureAccruedExpensesAndOtherCurrentLiabilitiesDetails" roleURI="http://www.hudsontech.com/role/DisclosureAccruedExpensesAndOtherCurrentLiabilitiesDetails" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureAcquisitionAssetsAcquiredAndLiabilitiesDetails" roleURI="http://www.hudsontech.com/role/DisclosureAcquisitionAssetsAcquiredAndLiabilitiesDetails" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureAcquisitionAdditionalInformationDetails" roleURI="http://www.hudsontech.com/role/DisclosureAcquisitionAdditionalInformationDetails" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureShareRepurchasesDetails" roleURI="http://www.hudsontech.com/role/DisclosureShareRepurchasesDetails" />
  <link:roleRef xlink:type="simple" xlink:href="hdsn-20260331.xsd#DisclosureSegmentInformationDetails" roleURI="http://www.hudsontech.com/role/DisclosureSegmentInformationDetails" />
  <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2025/ecd-2025.xsd#InsiderTradingArrangements" roleURI="http://xbrl.sec.gov/ecd/role/InsiderTradingArrangements" />
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DocumentDocumentAndEntityInformation" xlink:type="extended" xlink:title="995200090 - Document - Document and Entity Information">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_CoverAbstract" xlink:label="dei_CoverAbstract" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentType" xlink:label="dei_DocumentType_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_DocumentType_639138733435888799" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentQuarterlyReport" xlink:label="dei_DocumentQuarterlyReport_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_DocumentQuarterlyReport_639138733435888799" order="2" use="optional" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentPeriodEndDate" xlink:label="dei_DocumentPeriodEndDate_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_DocumentPeriodEndDate_639138733435888799" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentTransitionReport" xlink:label="dei_DocumentTransitionReport_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_DocumentTransitionReport_639138733435888799" order="4" use="optional" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityFileNumber" xlink:label="dei_EntityFileNumber_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_EntityFileNumber_639138733435888799" order="5" use="optional" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityRegistrantName" xlink:label="dei_EntityRegistrantName_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_EntityRegistrantName_639138733435888799" order="6" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityIncorporationStateCountryCode" xlink:label="dei_EntityIncorporationStateCountryCode_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_EntityIncorporationStateCountryCode_639138733435888799" order="7" use="optional" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityTaxIdentificationNumber" xlink:label="dei_EntityTaxIdentificationNumber_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_EntityTaxIdentificationNumber_639138733435888799" order="8" use="optional" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressAddressLine1" xlink:label="dei_EntityAddressAddressLine1_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_EntityAddressAddressLine1_639138733435888799" order="9" use="optional" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressAddressLine2" xlink:label="dei_EntityAddressAddressLine2_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_EntityAddressAddressLine2_639138733435888799" order="10" use="optional" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressCityOrTown" xlink:label="dei_EntityAddressCityOrTown_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_EntityAddressCityOrTown_639138733435888799" order="11" use="optional" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressStateOrProvince" xlink:label="dei_EntityAddressStateOrProvince_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_EntityAddressStateOrProvince_639138733435888799" order="12" use="optional" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressPostalZipCode" xlink:label="dei_EntityAddressPostalZipCode_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_EntityAddressPostalZipCode_639138733435888799" order="13" use="optional" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_CityAreaCode" xlink:label="dei_CityAreaCode_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_CityAreaCode_639138733435888799" order="14" use="optional" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_LocalPhoneNumber" xlink:label="dei_LocalPhoneNumber_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_LocalPhoneNumber_639138733435888799" order="15" use="optional" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_Security12bTitle" xlink:label="dei_Security12bTitle_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_Security12bTitle_639138733435888799" order="16" use="optional" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_TradingSymbol" xlink:label="dei_TradingSymbol_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_TradingSymbol_639138733435888799" order="17" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_SecurityExchangeName" xlink:label="dei_SecurityExchangeName_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_SecurityExchangeName_639138733435888799" order="18" use="optional" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityCurrentReportingStatus" xlink:label="dei_EntityCurrentReportingStatus_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_EntityCurrentReportingStatus_639138733435888799" order="19" use="optional" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityInteractiveDataCurrent" xlink:label="dei_EntityInteractiveDataCurrent_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_EntityInteractiveDataCurrent_639138733435888799" order="20" use="optional" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityFilerCategory" xlink:label="dei_EntityFilerCategory_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_EntityFilerCategory_639138733435888799" order="21" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntitySmallBusiness" xlink:label="dei_EntitySmallBusiness_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_EntitySmallBusiness_639138733435888799" order="22" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityEmergingGrowthCompany" xlink:label="dei_EntityEmergingGrowthCompany_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_EntityEmergingGrowthCompany_639138733435888799" order="23" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityShellCompany" xlink:label="dei_EntityShellCompany_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_EntityShellCompany_639138733435888799" order="24" use="optional" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityCommonStockSharesOutstanding" xlink:label="dei_EntityCommonStockSharesOutstanding_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_EntityCommonStockSharesOutstanding_639138733435888799" order="25" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityCentralIndexKey" xlink:label="dei_EntityCentralIndexKey_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_EntityCentralIndexKey_639138733435888799" order="26" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_CurrentFiscalYearEndDate" xlink:label="dei_CurrentFiscalYearEndDate_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_CurrentFiscalYearEndDate_639138733435888799" order="27" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentFiscalYearFocus" xlink:label="dei_DocumentFiscalYearFocus_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_DocumentFiscalYearFocus_639138733435888799" order="28" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentFiscalPeriodFocus" xlink:label="dei_DocumentFiscalPeriodFocus_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_DocumentFiscalPeriodFocus_639138733435888799" order="29" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_AmendmentFlag" xlink:label="dei_AmendmentFlag_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="dei_CoverAbstract" xlink:to="dei_AmendmentFlag_639138733435888799" order="30" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/StatementConsolidatedBalanceSheets" xlink:type="extended" xlink:title="995200100 - Statement - Consolidated Balance Sheets">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementOfFinancialPositionAbstract" xlink:label="loc_us-gaap_StatementOfFinancialPositionAbstract_20" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsAbstract" xlink:label="us-gaap_AssetsAbstract_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfFinancialPositionAbstract_20" xlink:to="us-gaap_AssetsAbstract_639138733435888799" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsCurrentAbstract" xlink:label="us-gaap_AssetsCurrentAbstract_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_AssetsAbstract_639138733435888799" xlink:to="us-gaap_AssetsCurrentAbstract_639138733435888799" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="us-gaap_CashAndCashEquivalentsAtCarryingValue_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_AssetsCurrentAbstract_639138733435888799" xlink:to="us-gaap_CashAndCashEquivalentsAtCarryingValue_639138733435888799" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountsReceivableNetCurrent" xlink:label="us-gaap_AccountsReceivableNetCurrent_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_AssetsCurrentAbstract_639138733435888799" xlink:to="us-gaap_AccountsReceivableNetCurrent_639138733435888799" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InventoryNet" xlink:label="us-gaap_InventoryNet_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_AssetsCurrentAbstract_639138733435888799" xlink:to="us-gaap_InventoryNet_639138733435888799" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxReceivable" xlink:label="us-gaap_IncomeTaxReceivable_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_AssetsCurrentAbstract_639138733435888799" xlink:to="us-gaap_IncomeTaxReceivable_639138733435888799" order="4" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:label="us-gaap_PrepaidExpenseAndOtherAssetsCurrent_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_AssetsCurrentAbstract_639138733435888799" xlink:to="us-gaap_PrepaidExpenseAndOtherAssetsCurrent_639138733435888799" order="5" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsCurrent" xlink:label="us-gaap_AssetsCurrent_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_AssetsCurrentAbstract_639138733435888799" xlink:to="us-gaap_AssetsCurrent_639138733435888799" order="6" use="optional" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="us-gaap_PropertyPlantAndEquipmentNet_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_AssetsAbstract_639138733435888799" xlink:to="us-gaap_PropertyPlantAndEquipmentNet_639138733435888799" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="4" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Goodwill" xlink:label="us-gaap_Goodwill_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_AssetsAbstract_639138733435888799" xlink:to="us-gaap_Goodwill_639138733435888799" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsNet" xlink:label="us-gaap_FiniteLivedIntangibleAssetsNet_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_AssetsAbstract_639138733435888799" xlink:to="us-gaap_FiniteLivedIntangibleAssetsNet_639138733435888799" order="4" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeaseRightOfUseAsset" xlink:label="us-gaap_OperatingLeaseRightOfUseAsset_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_AssetsAbstract_639138733435888799" xlink:to="us-gaap_OperatingLeaseRightOfUseAsset_639138733435888799" order="5" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherAssetsNoncurrent" xlink:label="us-gaap_OtherAssetsNoncurrent_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_AssetsAbstract_639138733435888799" xlink:to="us-gaap_OtherAssetsNoncurrent_639138733435888799" order="6" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Assets" xlink:label="us-gaap_Assets_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_AssetsAbstract_639138733435888799" xlink:to="us-gaap_Assets_639138733435888799" order="7" use="optional" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:label="us-gaap_LiabilitiesAndStockholdersEquityAbstract_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfFinancialPositionAbstract_20" xlink:to="us-gaap_LiabilitiesAndStockholdersEquityAbstract_639138733435888799" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesCurrentAbstract" xlink:label="us-gaap_LiabilitiesCurrentAbstract_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LiabilitiesAndStockholdersEquityAbstract_639138733435888799" xlink:to="us-gaap_LiabilitiesCurrentAbstract_639138733435888799" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountsPayableCurrent" xlink:label="us-gaap_AccountsPayableCurrent_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LiabilitiesCurrentAbstract_639138733435888799" xlink:to="us-gaap_AccountsPayableCurrent_639138733435888799" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_AccruedLiabilitiesAndOtherLiabilitiesCurrent" xlink:label="hdsn_AccruedLiabilitiesAndOtherLiabilitiesCurrent_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LiabilitiesCurrentAbstract_639138733435888799" xlink:to="hdsn_AccruedLiabilitiesAndOtherLiabilitiesCurrent_639138733435888799" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeRelatedLiabilitiesCurrent" xlink:label="us-gaap_EmployeeRelatedLiabilitiesCurrent_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LiabilitiesCurrentAbstract_639138733435888799" xlink:to="us-gaap_EmployeeRelatedLiabilitiesCurrent_639138733435888799" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesCurrent" xlink:label="us-gaap_LiabilitiesCurrent_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LiabilitiesCurrentAbstract_639138733435888799" xlink:to="us-gaap_LiabilitiesCurrent_639138733435888799" order="4" use="optional" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredIncomeTaxLiabilitiesNet" xlink:label="us-gaap_DeferredIncomeTaxLiabilitiesNet_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LiabilitiesAndStockholdersEquityAbstract_639138733435888799" xlink:to="us-gaap_DeferredIncomeTaxLiabilitiesNet_639138733435888799" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="4" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:label="us-gaap_OperatingLeaseLiabilityNoncurrent_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LiabilitiesAndStockholdersEquityAbstract_639138733435888799" xlink:to="us-gaap_OperatingLeaseLiabilityNoncurrent_639138733435888799" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringReserveNoncurrent" xlink:label="us-gaap_RestructuringReserveNoncurrent_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LiabilitiesAndStockholdersEquityAbstract_639138733435888799" xlink:to="us-gaap_RestructuringReserveNoncurrent_639138733435888799" order="4" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherLiabilitiesNoncurrent" xlink:label="us-gaap_OtherLiabilitiesNoncurrent_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LiabilitiesAndStockholdersEquityAbstract_639138733435888799" xlink:to="us-gaap_OtherLiabilitiesNoncurrent_639138733435888799" order="5" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Liabilities" xlink:label="us-gaap_Liabilities_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LiabilitiesAndStockholdersEquityAbstract_639138733435888799" xlink:to="us-gaap_Liabilities_639138733435888799" order="6" use="optional" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommitmentsAndContingencies" xlink:label="us-gaap_CommitmentsAndContingencies_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LiabilitiesAndStockholdersEquityAbstract_639138733435888799" xlink:to="us-gaap_CommitmentsAndContingencies_639138733435888799" order="7" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquityAbstract" xlink:label="us-gaap_StockholdersEquityAbstract_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LiabilitiesAndStockholdersEquityAbstract_639138733435888799" xlink:to="us-gaap_StockholdersEquityAbstract_639138733435888799" order="8" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PreferredStockValue" xlink:label="us-gaap_PreferredStockValue_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StockholdersEquityAbstract_639138733435888799" xlink:to="us-gaap_PreferredStockValue_639138733435888799" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockValue" xlink:label="us-gaap_CommonStockValue_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StockholdersEquityAbstract_639138733435888799" xlink:to="us-gaap_CommonStockValue_639138733435888799" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" priority="4" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalPaidInCapital" xlink:label="us-gaap_AdditionalPaidInCapital_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StockholdersEquityAbstract_639138733435888799" xlink:to="us-gaap_AdditionalPaidInCapital_639138733435888799" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StockholdersEquityAbstract_639138733435888799" xlink:to="us-gaap_RetainedEarningsAccumulatedDeficit_639138733435888799" order="4" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity" xlink:label="us-gaap_StockholdersEquity_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StockholdersEquityAbstract_639138733435888799" xlink:to="us-gaap_StockholdersEquity_639138733435888799" order="5" use="optional" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:label="us-gaap_LiabilitiesAndStockholdersEquity_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LiabilitiesAndStockholdersEquityAbstract_639138733435888799" xlink:to="us-gaap_LiabilitiesAndStockholdersEquity_639138733435888799" order="9" use="optional" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/StatementConsolidatedBalanceSheetsParenthetical" xlink:type="extended" xlink:title="995200105 - Statement - Consolidated Balance Sheets (Parenthetical)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementOfFinancialPositionAbstract" xlink:label="loc_us-gaap_StatementOfFinancialPositionAbstract_90" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfFinancialPositionAbstract_90" xlink:to="us-gaap_StatementTable_639138733435888799" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="us-gaap_StatementClassOfStockAxis_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StatementTable_639138733435888799" xlink:to="us-gaap_StatementClassOfStockAxis_639138733435888799" order="1" use="optional" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain" xlink:label="us-gaap_ClassOfStockDomain_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StatementClassOfStockAxis_639138733435888799" xlink:to="us-gaap_ClassOfStockDomain_639138733435888799" order="1" use="optional" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PreferredStockMember" xlink:label="us-gaap_PreferredStockMember_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ClassOfStockDomain_639138733435888799" xlink:to="us-gaap_PreferredStockMember_639138733435888799" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeriesAPreferredStockMember" xlink:label="us-gaap_SeriesAPreferredStockMember_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ClassOfStockDomain_639138733435888799" xlink:to="us-gaap_SeriesAPreferredStockMember_639138733435888799" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StatementTable_639138733435888799" xlink:to="us-gaap_StatementLineItems_639138733435888799" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent" xlink:label="us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StatementLineItems_639138733435888799" xlink:to="us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_639138733435888799" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PreferredStockParOrStatedValuePerShare" xlink:label="us-gaap_PreferredStockParOrStatedValuePerShare_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StatementLineItems_639138733435888799" xlink:to="us-gaap_PreferredStockParOrStatedValuePerShare_639138733435888799" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PreferredStockLiquidationPreferenceValue" xlink:label="us-gaap_PreferredStockLiquidationPreferenceValue_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StatementLineItems_639138733435888799" xlink:to="us-gaap_PreferredStockLiquidationPreferenceValue_639138733435888799" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PreferredStockSharesAuthorized" xlink:label="us-gaap_PreferredStockSharesAuthorized_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StatementLineItems_639138733435888799" xlink:to="us-gaap_PreferredStockSharesAuthorized_639138733435888799" order="4" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PreferredStockSharesIssued" xlink:label="us-gaap_PreferredStockSharesIssued_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StatementLineItems_639138733435888799" xlink:to="us-gaap_PreferredStockSharesIssued_639138733435888799" order="5" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PreferredStockSharesOutstanding" xlink:label="us-gaap_PreferredStockSharesOutstanding_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StatementLineItems_639138733435888799" xlink:to="us-gaap_PreferredStockSharesOutstanding_639138733435888799" order="6" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockParOrStatedValuePerShare" xlink:label="us-gaap_CommonStockParOrStatedValuePerShare_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StatementLineItems_639138733435888799" xlink:to="us-gaap_CommonStockParOrStatedValuePerShare_639138733435888799" order="7" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesAuthorized" xlink:label="us-gaap_CommonStockSharesAuthorized_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StatementLineItems_639138733435888799" xlink:to="us-gaap_CommonStockSharesAuthorized_639138733435888799" order="8" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesIssued" xlink:label="us-gaap_CommonStockSharesIssued_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StatementLineItems_639138733435888799" xlink:to="us-gaap_CommonStockSharesIssued_639138733435888799" order="9" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesOutstanding" xlink:label="us-gaap_CommonStockSharesOutstanding_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StatementLineItems_639138733435888799" xlink:to="us-gaap_CommonStockSharesOutstanding_639138733435888799" order="10" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/StatementConsolidatedStatementsOfIncome" xlink:type="extended" xlink:title="995200200 - Statement - Consolidated Statements of Income">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementAbstract" xlink:label="us-gaap_IncomeStatementAbstract" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax" xlink:label="us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_IncomeStatementAbstract" xlink:to="us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax_639138733435888799" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostOfRevenue" xlink:label="us-gaap_CostOfRevenue_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_IncomeStatementAbstract" xlink:to="us-gaap_CostOfRevenue_639138733435888799" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GrossProfit" xlink:label="us-gaap_GrossProfit_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_IncomeStatementAbstract" xlink:to="us-gaap_GrossProfit_639138733435888799" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingExpensesAbstract" xlink:label="us-gaap_OperatingExpensesAbstract_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_IncomeStatementAbstract" xlink:to="us-gaap_OperatingExpensesAbstract_639138733435888799" order="4" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SellingGeneralAndAdministrativeExpense" xlink:label="us-gaap_SellingGeneralAndAdministrativeExpense_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_OperatingExpensesAbstract_639138733435888799" xlink:to="us-gaap_SellingGeneralAndAdministrativeExpense_639138733435888799" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdjustmentForAmortization" xlink:label="us-gaap_AdjustmentForAmortization_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_OperatingExpensesAbstract_639138733435888799" xlink:to="us-gaap_AdjustmentForAmortization_639138733435888799" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingExpenses" xlink:label="us-gaap_OperatingExpenses_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_OperatingExpensesAbstract_639138733435888799" xlink:to="us-gaap_OperatingExpenses_639138733435888799" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingIncomeLoss" xlink:label="us-gaap_OperatingIncomeLoss_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_IncomeStatementAbstract" xlink:to="us-gaap_OperatingIncomeLoss_639138733435888799" order="5" use="optional" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherNoncashIncomeExpenseAbstract" xlink:label="us-gaap_OtherNoncashIncomeExpenseAbstract_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_IncomeStatementAbstract" xlink:to="us-gaap_OtherNoncashIncomeExpenseAbstract_639138733435888799" order="6" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestIncomeExpenseNonoperatingNet" xlink:label="us-gaap_InterestIncomeExpenseNonoperatingNet_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_OtherNoncashIncomeExpenseAbstract_639138733435888799" xlink:to="us-gaap_InterestIncomeExpenseNonoperatingNet_639138733435888799" order="1" use="optional" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:label="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_IncomeStatementAbstract" xlink:to="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_639138733435888799" order="7" use="optional" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="us-gaap_IncomeTaxExpenseBenefit_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_IncomeStatementAbstract" xlink:to="us-gaap_IncomeTaxExpenseBenefit_639138733435888799" order="8" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss" xlink:label="us-gaap_NetIncomeLoss_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_IncomeStatementAbstract" xlink:to="us-gaap_NetIncomeLoss_639138733435888799" order="9" use="optional" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareBasic" xlink:label="us-gaap_EarningsPerShareBasic_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_IncomeStatementAbstract" xlink:to="us-gaap_EarningsPerShareBasic_639138733435888799" order="10" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareDiluted" xlink:label="us-gaap_EarningsPerShareDiluted_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_IncomeStatementAbstract" xlink:to="us-gaap_EarningsPerShareDiluted_639138733435888799" order="11" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:label="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_IncomeStatementAbstract" xlink:to="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_639138733435888799" order="12" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:label="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_IncomeStatementAbstract" xlink:to="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_639138733435888799" order="13" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/StatementConsolidatedStatementsOfStockholdersEquity" xlink:type="extended" xlink:title="995200300 - Statement - Consolidated Statements of Stockholders' Equity">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquityAbstract" xlink:label="loc_us-gaap_StockholdersEquityAbstract_266412" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StockholdersEquityAbstract_266412" xlink:to="us-gaap_StatementTable_639138733435888799" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="us-gaap_StatementEquityComponentsAxis_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StatementTable_639138733435888799" xlink:to="us-gaap_StatementEquityComponentsAxis_639138733435888799" order="1" use="optional" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockMember" xlink:label="us-gaap_CommonStockMember_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StatementEquityComponentsAxis_639138733435888799" xlink:to="us-gaap_CommonStockMember_639138733435888799" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="us-gaap_AdditionalPaidInCapitalMember_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StatementEquityComponentsAxis_639138733435888799" xlink:to="us-gaap_AdditionalPaidInCapitalMember_639138733435888799" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetainedEarningsMember" xlink:label="us-gaap_RetainedEarningsMember_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StatementEquityComponentsAxis_639138733435888799" xlink:to="us-gaap_RetainedEarningsMember_639138733435888799" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain" xlink:label="us-gaap_EquityComponentDomain_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StatementEquityComponentsAxis_639138733435888799" xlink:to="us-gaap_EquityComponentDomain_639138733435888799" order="4" use="optional" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems_639138733435888799" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StatementTable_639138733435888799" xlink:to="us-gaap_StatementLineItems_639138733435888799" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity" xlink:label="us-gaap_StockholdersEquity_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StatementLineItems_639138733435888799" xlink:to="us-gaap_StockholdersEquity_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/periodStartLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharesIssued" xlink:label="us-gaap_SharesIssued_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StatementLineItems_639138733435888799" xlink:to="us-gaap_SharesIssued_639138733436045438" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/periodStartLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised" xlink:label="us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StatementLineItems_639138733435888799" xlink:to="us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_639138733436045438" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" priority="4" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:label="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_639138733436045438" xlink:to="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodValue" xlink:label="us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StatementLineItems_639138733435888799" xlink:to="us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_639138733436045438" order="4" use="optional" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodShares" xlink:label="us-gaap_StockRepurchasedAndRetiredDuringPeriodShares_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_639138733436045438" xlink:to="us-gaap_StockRepurchasedAndRetiredDuringPeriodShares_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_AdjustmentsToAdditionalPaidInCapitalExcessTaxBenefitsFromStockOptionExercises" xlink:label="hdsn_AdjustmentsToAdditionalPaidInCapitalExcessTaxBenefitsFromStockOptionExercises_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StatementLineItems_639138733435888799" xlink:to="hdsn_AdjustmentsToAdditionalPaidInCapitalExcessTaxBenefitsFromStockOptionExercises_639138733436045438" order="5" use="optional" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:label="us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StatementLineItems_639138733435888799" xlink:to="us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_639138733436045438" order="6" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="7" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss" xlink:label="us-gaap_NetIncomeLoss_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StatementLineItems_639138733435888799" xlink:to="us-gaap_NetIncomeLoss_639138733436045438" order="7" use="optional" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity" xlink:label="us-gaap_StockholdersEquity_6391387334360454381" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StatementLineItems_639138733435888799" xlink:to="us-gaap_StockholdersEquity_6391387334360454381" order="8" use="optional" preferredLabel="http://www.xbrl.org/2003/role/periodEndLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharesIssued" xlink:label="us-gaap_SharesIssued_6391387334360454381" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StatementLineItems_639138733435888799" xlink:to="us-gaap_SharesIssued_6391387334360454381" order="9" use="optional" preferredLabel="http://www.xbrl.org/2003/role/periodEndLabel" priority="1" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/StatementConsolidatedStatementsOfCashFlows" xlink:type="extended" xlink:title="995200400 - Statement - Consolidated Statements of Cash Flows">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementOfCashFlowsAbstract" xlink:label="loc_us-gaap_StatementOfCashFlowsAbstract_354" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfCashFlowsAbstract_354" xlink:to="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProfitLoss" xlink:label="us-gaap_ProfitLoss_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_639138733436045438" xlink:to="us-gaap_ProfitLoss_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:label="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_639138733436045438" xlink:to="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_639138733436045438" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DepreciationDepletionAndAmortization" xlink:label="us-gaap_DepreciationDepletionAndAmortization_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_639138733436045438" xlink:to="us-gaap_DepreciationDepletionAndAmortization_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AmortizationOfIntangibleAssets" xlink:label="us-gaap_AmortizationOfIntangibleAssets_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_639138733436045438" xlink:to="us-gaap_AmortizationOfIntangibleAssets_639138733436045438" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InventoryWriteDown" xlink:label="us-gaap_InventoryWriteDown_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_639138733436045438" xlink:to="us-gaap_InventoryWriteDown_639138733436045438" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProvisionForDoubtfulAccounts" xlink:label="us-gaap_ProvisionForDoubtfulAccounts_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_639138733436045438" xlink:to="us-gaap_ProvisionForDoubtfulAccounts_639138733436045438" order="4" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensation" xlink:label="us-gaap_ShareBasedCompensation_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_639138733436045438" xlink:to="us-gaap_ShareBasedCompensation_639138733436045438" order="5" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="3" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AmortizationOfFinancingCosts" xlink:label="us-gaap_AmortizationOfFinancingCosts_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_639138733436045438" xlink:to="us-gaap_AmortizationOfFinancingCosts_639138733436045438" order="6" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:label="us-gaap_DeferredIncomeTaxExpenseBenefit_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_639138733436045438" xlink:to="us-gaap_DeferredIncomeTaxExpenseBenefit_639138733436045438" order="7" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:label="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_639138733436045438" xlink:to="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_639138733436045438" order="8" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInAccountsReceivable" xlink:label="us-gaap_IncreaseDecreaseInAccountsReceivable_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_639138733436045438" xlink:to="us-gaap_IncreaseDecreaseInAccountsReceivable_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInInventories" xlink:label="us-gaap_IncreaseDecreaseInInventories_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_639138733436045438" xlink:to="us-gaap_IncreaseDecreaseInInventories_639138733436045438" order="2" use="optional" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" xlink:label="us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_639138733436045438" xlink:to="us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_639138733436045438" order="3" use="optional" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInIncomeTaxesReceivable" xlink:label="us-gaap_IncreaseDecreaseInIncomeTaxesReceivable_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_639138733436045438" xlink:to="us-gaap_IncreaseDecreaseInIncomeTaxesReceivable_639138733436045438" order="4" use="optional" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities" xlink:label="us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_639138733436045438" xlink:to="us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_639138733436045438" order="5" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivities_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_639138733436045438" xlink:to="us-gaap_NetCashProvidedByUsedInOperatingActivities_639138733436045438" order="6" use="optional" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfCashFlowsAbstract_354" xlink:to="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_639138733436045438" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:label="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_639138733436045438" xlink:to="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivities_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_639138733436045438" xlink:to="us-gaap_NetCashProvidedByUsedInInvestingActivities_639138733436045438" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfCashFlowsAbstract_354" xlink:to="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_639138733436045438" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation" xlink:label="us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_639138733436045438" xlink:to="us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsForRepurchaseOfCommonStock" xlink:label="us-gaap_PaymentsForRepurchaseOfCommonStock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_639138733436045438" xlink:to="us-gaap_PaymentsForRepurchaseOfCommonStock_639138733436045438" order="2" use="optional" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivities_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_639138733436045438" xlink:to="us-gaap_NetCashProvidedByUsedInFinancingActivities_639138733436045438" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfCashFlowsAbstract_354" xlink:to="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect_639138733436045438" order="4" use="optional" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfCashFlowsAbstract_354" xlink:to="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_639138733436045438" order="5" use="optional" preferredLabel="http://www.xbrl.org/2003/role/periodStartLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_6391387334360454381" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfCashFlowsAbstract_354" xlink:to="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_6391387334360454381" order="6" use="optional" preferredLabel="http://www.xbrl.org/2003/role/periodEndLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SupplementalCashFlowInformationAbstract" xlink:label="us-gaap_SupplementalCashFlowInformationAbstract_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfCashFlowsAbstract_354" xlink:to="us-gaap_SupplementalCashFlowInformationAbstract_639138733436045438" order="7" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestPaidNet" xlink:label="us-gaap_InterestPaidNet_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_SupplementalCashFlowInformationAbstract_639138733436045438" xlink:to="us-gaap_InterestPaidNet_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxesPaidNet" xlink:label="us-gaap_IncomeTaxesPaidNet_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_SupplementalCashFlowInformationAbstract_639138733436045438" xlink:to="us-gaap_IncomeTaxesPaidNet_639138733436045438" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" priority="8" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CapitalExpendituresIncurredButNotYetPaid" xlink:label="us-gaap_CapitalExpendituresIncurredButNotYetPaid_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_SupplementalCashFlowInformationAbstract_639138733436045438" xlink:to="us-gaap_CapitalExpendituresIncurredButNotYetPaid_639138733436045438" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureSummaryOfSignificantAccountingPolicies" xlink:type="extended" xlink:title="995210101 - Disclosure - Summary of Significant Accounting Policies">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountingPoliciesAbstract" xlink:label="loc_us-gaap_AccountingPoliciesAbstract_529" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SignificantAccountingPoliciesTextBlock" xlink:label="us-gaap_SignificantAccountingPoliciesTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_529" xlink:to="us-gaap_SignificantAccountingPoliciesTextBlock_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureFairValue" xlink:type="extended" xlink:title="995210201 - Disclosure - Fair Value">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueDisclosuresAbstract" xlink:label="loc_us-gaap_FairValueDisclosuresAbstract_532" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementInputsDisclosureTextBlock" xlink:label="us-gaap_FairValueMeasurementInputsDisclosureTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FairValueDisclosuresAbstract_532" xlink:to="us-gaap_FairValueMeasurementInputsDisclosureTextBlock_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureInventories" xlink:type="extended" xlink:title="995210301 - Disclosure - Inventories">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InventoryDisclosureAbstract" xlink:label="loc_us-gaap_InventoryDisclosureAbstract_2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InventoryDisclosureTextBlock" xlink:label="us-gaap_InventoryDisclosureTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_InventoryDisclosureAbstract_2" xlink:to="us-gaap_InventoryDisclosureTextBlock_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosurePropertyPlantAndEquipment" xlink:type="extended" xlink:title="995210401 - Disclosure - Property, plant and equipment">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentAbstract" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAbstract_5" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentDisclosureTextBlock" xlink:label="us-gaap_PropertyPlantAndEquipmentDisclosureTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAbstract_5" xlink:to="us-gaap_PropertyPlantAndEquipmentDisclosureTextBlock_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureLeases" xlink:type="extended" xlink:title="995210501 - Disclosure - Leases">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LeasesAbstract" xlink:label="loc_us-gaap_LeasesAbstract_405283" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LesseeOperatingLeasesTextBlock" xlink:label="us-gaap_LesseeOperatingLeasesTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LeasesAbstract_405283" xlink:to="us-gaap_LesseeOperatingLeasesTextBlock_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureGoodwillAndIntangibleAssets" xlink:type="extended" xlink:title="995210601 - Disclosure - Goodwill and intangible assets">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract" xlink:label="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract_8" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillAndIntangibleAssetsDisclosureTextBlock" xlink:label="us-gaap_GoodwillAndIntangibleAssetsDisclosureTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract_8" xlink:to="us-gaap_GoodwillAndIntangibleAssetsDisclosureTextBlock_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureShareBasedCompensation" xlink:type="extended" xlink:title="995210701 - Disclosure - Share-Based Compensation">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationAbstract" xlink:label="loc_us-gaap_ShareBasedCompensationAbstract_11" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock" xlink:label="us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationAbstract_11" xlink:to="us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureShortTermAndLongTermDebt" xlink:type="extended" xlink:title="995210801 - Disclosure - Short-term and long-term debt">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtDisclosureAbstract" xlink:label="loc_us-gaap_DebtDisclosureAbstract_14" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtDisclosureTextBlock" xlink:label="us-gaap_DebtDisclosureTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtDisclosureAbstract_14" xlink:to="us-gaap_DebtDisclosureTextBlock_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureAccruedExpensesAndOtherCurrentLiabilities" xlink:type="extended" xlink:title="995210901 - Disclosure - Accrued expenses and other current liabilities">
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_AccruedExpensesAndOtherCurrentLiabilitiesAbstract" xlink:label="hdsn_AccruedExpensesAndOtherCurrentLiabilitiesAbstract" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountsPayableAccruedLiabilitiesAndOtherLiabilitiesDisclosureCurrentTextBlock" xlink:label="us-gaap_AccountsPayableAccruedLiabilitiesAndOtherLiabilitiesDisclosureCurrentTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="hdsn_AccruedExpensesAndOtherCurrentLiabilitiesAbstract" xlink:to="us-gaap_AccountsPayableAccruedLiabilitiesAndOtherLiabilitiesDisclosureCurrentTextBlock_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureAcquisition" xlink:type="extended" xlink:title="995211001 - Disclosure - Acquisition">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationsAbstract" xlink:label="us-gaap_BusinessCombinationsAbstract" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationDisclosureTextBlock" xlink:label="us-gaap_BusinessCombinationDisclosureTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_BusinessCombinationsAbstract" xlink:to="us-gaap_BusinessCombinationDisclosureTextBlock_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureShareRepurchases" xlink:type="extended" xlink:title="995211101 - Disclosure - Share repurchases">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquityNoteAbstract" xlink:label="us-gaap_StockholdersEquityNoteAbstract" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquityNoteDisclosureTextBlock" xlink:label="us-gaap_StockholdersEquityNoteDisclosureTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StockholdersEquityNoteAbstract" xlink:to="us-gaap_StockholdersEquityNoteDisclosureTextBlock_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureSegmentInformation" xlink:type="extended" xlink:title="995211201 - Disclosure - Segment information">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingAbstract" xlink:label="us-gaap_SegmentReportingAbstract" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingDisclosureTextBlock" xlink:label="us-gaap_SegmentReportingDisclosureTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_SegmentReportingAbstract" xlink:to="us-gaap_SegmentReportingDisclosureTextBlock_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureSummaryOfSignificantAccountingPoliciesPolicies" xlink:type="extended" xlink:title="99920102 - Disclosure - Summary of Significant Accounting Policies (Policies)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountingPoliciesAbstract" xlink:label="loc_us-gaap_AccountingPoliciesAbstract_60" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_NatureOfOperationsPolicyPolicyTextBlock" xlink:label="hdsn_NatureOfOperationsPolicyPolicyTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_60" xlink:to="hdsn_NatureOfOperationsPolicyPolicyTextBlock_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConsolidationPolicyTextBlock" xlink:label="us-gaap_ConsolidationPolicyTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_60" xlink:to="us-gaap_ConsolidationPolicyTextBlock_639138733436045438" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueOfFinancialInstrumentsPolicy" xlink:label="us-gaap_FairValueOfFinancialInstrumentsPolicy_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_60" xlink:to="us-gaap_FairValueOfFinancialInstrumentsPolicy_639138733436045438" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskCreditRisk" xlink:label="us-gaap_ConcentrationRiskCreditRisk_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_60" xlink:to="us-gaap_ConcentrationRiskCreditRisk_639138733436045438" order="4" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsPolicyTextBlock" xlink:label="us-gaap_CashAndCashEquivalentsPolicyTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_60" xlink:to="us-gaap_CashAndCashEquivalentsPolicyTextBlock_639138733436045438" order="5" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InventoryPolicyTextBlock" xlink:label="us-gaap_InventoryPolicyTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_60" xlink:to="us-gaap_InventoryPolicyTextBlock_639138733436045438" order="6" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentPolicyTextBlock" xlink:label="us-gaap_PropertyPlantAndEquipmentPolicyTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_60" xlink:to="us-gaap_PropertyPlantAndEquipmentPolicyTextBlock_639138733436045438" order="7" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillAndIntangibleAssetsPolicyTextBlock" xlink:label="us-gaap_GoodwillAndIntangibleAssetsPolicyTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_60" xlink:to="us-gaap_GoodwillAndIntangibleAssetsPolicyTextBlock_639138733436045438" order="8" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LesseeLeasesPolicyTextBlock" xlink:label="us-gaap_LesseeLeasesPolicyTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_60" xlink:to="us-gaap_LesseeLeasesPolicyTextBlock_639138733436045438" order="9" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_CylinderDepositLiabilityPolicyPolicyTextBlock" xlink:label="hdsn_CylinderDepositLiabilityPolicyPolicyTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_60" xlink:to="hdsn_CylinderDepositLiabilityPolicyPolicyTextBlock_639138733436045438" order="10" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerPolicyTextBlock" xlink:label="us-gaap_RevenueFromContractWithCustomerPolicyTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_60" xlink:to="us-gaap_RevenueFromContractWithCustomerPolicyTextBlock_639138733436045438" order="11" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxPolicyTextBlock" xlink:label="us-gaap_IncomeTaxPolicyTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_60" xlink:to="us-gaap_IncomeTaxPolicyTextBlock_639138733436045438" order="12" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerSharePolicyTextBlock" xlink:label="us-gaap_EarningsPerSharePolicyTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_60" xlink:to="us-gaap_EarningsPerSharePolicyTextBlock_639138733436045438" order="13" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="4" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UseOfEstimates" xlink:label="us-gaap_UseOfEstimates_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_60" xlink:to="us-gaap_UseOfEstimates_639138733436045438" order="14" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ImpairmentOrDisposalOfLongLivedAssetsPolicyTextBlock" xlink:label="us-gaap_ImpairmentOrDisposalOfLongLivedAssetsPolicyTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_60" xlink:to="us-gaap_ImpairmentOrDisposalOfLongLivedAssetsPolicyTextBlock_639138733436045438" order="15" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ResearchDevelopmentAndComputerSoftwarePolicyTextBlock" xlink:label="us-gaap_ResearchDevelopmentAndComputerSoftwarePolicyTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_60" xlink:to="us-gaap_ResearchDevelopmentAndComputerSoftwarePolicyTextBlock_639138733436045438" order="16" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock" xlink:label="us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_60" xlink:to="us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock_639138733436045438" order="17" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureSummaryOfSignificantAccountingPoliciesTables" xlink:type="extended" xlink:title="99930103 - Disclosure - Summary of Significant Accounting Policies (Tables)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountingPoliciesAbstract" xlink:label="loc_us-gaap_AccountingPoliciesAbstract_77" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueTableTextBlock" xlink:label="us-gaap_DisaggregationOfRevenueTableTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_77" xlink:to="us-gaap_DisaggregationOfRevenueTableTextBlock_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock" xlink:label="us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_77" xlink:to="us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock_639138733436045438" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureInventoriesTables" xlink:type="extended" xlink:title="99930303 - Disclosure - Inventories (Tables)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InventoryDisclosureAbstract" xlink:label="loc_us-gaap_InventoryDisclosureAbstract_81" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfInventoryCurrentTableTextBlock" xlink:label="us-gaap_ScheduleOfInventoryCurrentTableTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_InventoryDisclosureAbstract_81" xlink:to="us-gaap_ScheduleOfInventoryCurrentTableTextBlock_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosurePropertyPlantAndEquipmentTables" xlink:type="extended" xlink:title="99930403 - Disclosure - Property, plant and equipment (Tables)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentAbstract" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAbstract_84" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTextBlock" xlink:label="us-gaap_PropertyPlantAndEquipmentTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAbstract_84" xlink:to="us-gaap_PropertyPlantAndEquipmentTextBlock_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureLeasesTables" xlink:type="extended" xlink:title="99930503 - Disclosure - Leases (Tables)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LeasesAbstract" xlink:label="loc_us-gaap_LeasesAbstract_405290" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LeasesAbstract_405290" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="2" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_ScheduleOfOperatingLeaseInBalanceSheetClassificationTableTextBlock" xlink:label="hdsn_ScheduleOfOperatingLeaseInBalanceSheetClassificationTableTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LeasesAbstract_405290" xlink:to="hdsn_ScheduleOfOperatingLeaseInBalanceSheetClassificationTableTextBlock_639138733436045438" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" priority="2" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_ScheduleOfOperatingLeaseOtherInformationTableTextBlock" xlink:label="hdsn_ScheduleOfOperatingLeaseOtherInformationTableTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LeasesAbstract_405290" xlink:to="hdsn_ScheduleOfOperatingLeaseOtherInformationTableTextBlock_639138733436045438" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" priority="2" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_ScheduleOfSupplementalCashFlowAndNonCashInformationRelatedToLeasesTableTextBlock" xlink:label="hdsn_ScheduleOfSupplementalCashFlowAndNonCashInformationRelatedToLeasesTableTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LeasesAbstract_405290" xlink:to="hdsn_ScheduleOfSupplementalCashFlowAndNonCashInformationRelatedToLeasesTableTextBlock_639138733436045438" order="4" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureGoodwillAndIntangibleAssetsTables" xlink:type="extended" xlink:title="99930603 - Disclosure - Goodwill and intangible assets (Tables)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract" xlink:label="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract_87" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTableTextBlock" xlink:label="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTableTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract_87" xlink:to="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTableTextBlock_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="4" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureShareBasedCompensationTables" xlink:type="extended" xlink:title="99930703 - Disclosure - Share-Based Compensation (Tables)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationAbstract" xlink:label="loc_us-gaap_ShareBasedCompensationAbstract_109" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock" xlink:label="us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationAbstract_109" xlink:to="us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationActivityTableTextBlock" xlink:label="us-gaap_ScheduleOfShareBasedCompensationActivityTableTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationAbstract_109" xlink:to="us-gaap_ScheduleOfShareBasedCompensationActivityTableTextBlock_639138733436045438" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureAccruedExpensesAndOtherCurrentLiabilitiesTables" xlink:type="extended" xlink:title="99930903 - Disclosure - Accrued expenses and other current liabilities (Tables)">
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_AccruedExpensesAndOtherCurrentLiabilitiesAbstract" xlink:label="hdsn_AccruedExpensesAndOtherCurrentLiabilitiesAbstract_1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfAccountsPayableAndAccruedLiabilitiesTableTextBlock" xlink:label="us-gaap_ScheduleOfAccountsPayableAndAccruedLiabilitiesTableTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="hdsn_AccruedExpensesAndOtherCurrentLiabilitiesAbstract_1" xlink:to="us-gaap_ScheduleOfAccountsPayableAndAccruedLiabilitiesTableTextBlock_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureAcquisitionTables" xlink:type="extended" xlink:title="99931003 - Disclosure - Acquisition (Tables)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationsAbstract" xlink:label="us-gaap_BusinessCombinationsAbstract_1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock" xlink:label="us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_BusinessCombinationsAbstract_1" xlink:to="us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureSegmentInformationTables" xlink:type="extended" xlink:title="99931203 - Disclosure - Segment information (Tables)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingAbstract" xlink:label="us-gaap_SegmentReportingAbstract_1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock" xlink:label="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_SegmentReportingAbstract_1" xlink:to="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureSummaryOfSignificantAccountingPoliciesDetails" xlink:type="extended" xlink:title="99940101 - Disclosure - Summary of Significant Accounting Policies (Details)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountingPoliciesAbstract" xlink:label="loc_us-gaap_AccountingPoliciesAbstract_142" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_SignificantAccountingPoliciesTable" xlink:label="hdsn_SignificantAccountingPoliciesTable_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_142" xlink:to="hdsn_SignificantAccountingPoliciesTable_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskByTypeAxis" xlink:label="us-gaap_ConcentrationRiskByTypeAxis_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="hdsn_SignificantAccountingPoliciesTable_639138733436045438" xlink:to="us-gaap_ConcentrationRiskByTypeAxis_639138733436045438" order="1" use="optional" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="us-gaap_ConcentrationRiskTypeDomain_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ConcentrationRiskByTypeAxis_639138733436045438" xlink:to="us-gaap_ConcentrationRiskTypeDomain_639138733436045438" order="1" use="optional" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CustomerConcentrationRiskMember" xlink:label="us-gaap_CustomerConcentrationRiskMember_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ConcentrationRiskTypeDomain_639138733436045438" xlink:to="us-gaap_CustomerConcentrationRiskMember_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MajorCustomersAxis" xlink:label="srt_MajorCustomersAxis_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="hdsn_SignificantAccountingPoliciesTable_639138733436045438" xlink:to="srt_MajorCustomersAxis_639138733436045438" order="2" use="optional" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_NameOfMajorCustomerDomain" xlink:label="srt_NameOfMajorCustomerDomain_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_MajorCustomersAxis_639138733436045438" xlink:to="srt_NameOfMajorCustomerDomain_639138733436045438" order="1" use="optional" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_UnitedStatesDefenseLogisticsAgencyMember" xlink:label="hdsn_UnitedStatesDefenseLogisticsAgencyMember_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_NameOfMajorCustomerDomain_639138733436045438" xlink:to="hdsn_UnitedStatesDefenseLogisticsAgencyMember_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:label="us-gaap_ConcentrationRiskByBenchmarkAxis_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="hdsn_SignificantAccountingPoliciesTable_639138733436045438" xlink:to="us-gaap_ConcentrationRiskByBenchmarkAxis_639138733436045438" order="3" use="optional" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="us-gaap_ConcentrationRiskBenchmarkDomain_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ConcentrationRiskByBenchmarkAxis_639138733436045438" xlink:to="us-gaap_ConcentrationRiskBenchmarkDomain_639138733436045438" order="1" use="optional" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerMember" xlink:label="us-gaap_RevenueFromContractWithCustomerMember_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ConcentrationRiskBenchmarkDomain_639138733436045438" xlink:to="us-gaap_RevenueFromContractWithCustomerMember_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountsReceivableMember" xlink:label="us-gaap_AccountsReceivableMember_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ConcentrationRiskBenchmarkDomain_639138733436045438" xlink:to="us-gaap_AccountsReceivableMember_639138733436045438" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="hdsn_SignificantAccountingPoliciesTable_639138733436045438" xlink:to="srt_ProductOrServiceAxis_639138733436045438" order="4" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_ProductOrServiceAxis_639138733436045438" xlink:to="srt_ProductsAndServicesDomain_639138733436045438" order="1" use="optional" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ManagementServiceMember" xlink:label="us-gaap_ManagementServiceMember_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_ProductsAndServicesDomain_639138733436045438" xlink:to="us-gaap_ManagementServiceMember_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityAxis" xlink:label="us-gaap_IncomeTaxAuthorityAxis_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="hdsn_SignificantAccountingPoliciesTable_639138733436045438" xlink:to="us-gaap_IncomeTaxAuthorityAxis_639138733436045438" order="5" use="optional" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="us-gaap_IncomeTaxAuthorityDomain_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_IncomeTaxAuthorityAxis_639138733436045438" xlink:to="us-gaap_IncomeTaxAuthorityDomain_639138733436045438" order="1" use="optional" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DomesticCountryMember" xlink:label="us-gaap_DomesticCountryMember_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_IncomeTaxAuthorityDomain_639138733436045438" xlink:to="us-gaap_DomesticCountryMember_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StateAndLocalJurisdictionMember" xlink:label="us-gaap_StateAndLocalJurisdictionMember_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_IncomeTaxAuthorityDomain_639138733436045438" xlink:to="us-gaap_StateAndLocalJurisdictionMember_639138733436045438" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_SignificantAccountingPoliciesLineItems" xlink:label="hdsn_SignificantAccountingPoliciesLineItems_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="hdsn_SignificantAccountingPoliciesTable_639138733436045438" xlink:to="hdsn_SignificantAccountingPoliciesLineItems_639138733436045438" order="6" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NumberOfReportableSegments" xlink:label="us-gaap_NumberOfReportableSegments_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="hdsn_SignificantAccountingPoliciesLineItems_639138733436045438" xlink:to="us-gaap_NumberOfReportableSegments_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskPercentage1" xlink:label="us-gaap_ConcentrationRiskPercentage1_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="hdsn_SignificantAccountingPoliciesLineItems_639138733436045438" xlink:to="us-gaap_ConcentrationRiskPercentage1_639138733436045438" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Revenues" xlink:label="us-gaap_Revenues_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="hdsn_SignificantAccountingPoliciesLineItems_639138733436045438" xlink:to="us-gaap_Revenues_639138733436045438" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountsReceivableNet" xlink:label="us-gaap_AccountsReceivableNet_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="hdsn_SignificantAccountingPoliciesLineItems_639138733436045438" xlink:to="us-gaap_AccountsReceivableNet_639138733436045438" order="4" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NumberOfReportingUnits" xlink:label="us-gaap_NumberOfReportingUnits_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="hdsn_SignificantAccountingPoliciesLineItems_639138733436045438" xlink:to="us-gaap_NumberOfReportingUnits_639138733436045438" order="5" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillImpairmentLoss" xlink:label="us-gaap_GoodwillImpairmentLoss_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="hdsn_SignificantAccountingPoliciesLineItems_639138733436045438" xlink:to="us-gaap_GoodwillImpairmentLoss_639138733436045438" order="6" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CustomerRefundLiabilityCurrent" xlink:label="us-gaap_CustomerRefundLiabilityCurrent_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="hdsn_SignificantAccountingPoliciesLineItems_639138733436045438" xlink:to="us-gaap_CustomerRefundLiabilityCurrent_639138733436045438" order="7" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_ContractTerm" xlink:label="hdsn_ContractTerm_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="hdsn_SignificantAccountingPoliciesLineItems_639138733436045438" xlink:to="hdsn_ContractTerm_639138733436045438" order="8" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_RenewalTerm" xlink:label="hdsn_RenewalTerm_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="hdsn_SignificantAccountingPoliciesLineItems_639138733436045438" xlink:to="hdsn_RenewalTerm_639138733436045438" order="9" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax" xlink:label="us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="hdsn_SignificantAccountingPoliciesLineItems_639138733436045438" xlink:to="us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax_639138733436045438" order="10" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLossCarryforwards" xlink:label="us-gaap_OperatingLossCarryforwards_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="hdsn_SignificantAccountingPoliciesLineItems_639138733436045438" xlink:to="us-gaap_OperatingLossCarryforwards_639138733436045438" order="11" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureSummaryOfSignificantAccountingPoliciesRevenuesDetails" xlink:type="extended" xlink:title="99940102 - Disclosure - Summary of Significant Accounting Policies - Revenues (Details)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountingPoliciesAbstract" xlink:label="us-gaap_AccountingPoliciesAbstract" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable" xlink:label="us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable_639138733436045438" xlink:to="srt_ProductOrServiceAxis_639138733436045438" order="1" use="optional" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_ProductOrServiceAxis_639138733436045438" xlink:to="srt_ProductsAndServicesDomain_639138733436045438" order="1" use="optional" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProductMember" xlink:label="us-gaap_ProductMember_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_ProductsAndServicesDomain_639138733436045438" xlink:to="us-gaap_ProductMember_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ServiceMember" xlink:label="us-gaap_ServiceMember_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_ProductsAndServicesDomain_639138733436045438" xlink:to="us-gaap_ServiceMember_639138733436045438" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingRevenueReconcilingItemLineItems" xlink:label="us-gaap_SegmentReportingRevenueReconcilingItemLineItems_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable_639138733436045438" xlink:to="us-gaap_SegmentReportingRevenueReconcilingItemLineItems_639138733436045438" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax" xlink:label="us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_SegmentReportingRevenueReconcilingItemLineItems_639138733436045438" xlink:to="us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="2" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureSummaryOfSignificantAccountingPoliciesIncomePerShareDetails" xlink:type="extended" xlink:title="99940103 - Disclosure - Summary of Significant Accounting Policies - Income per share (Details)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountingPoliciesAbstract" xlink:label="us-gaap_AccountingPoliciesAbstract" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss" xlink:label="us-gaap_NetIncomeLoss_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_NetIncomeLoss_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:label="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_639138733436045438" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements" xlink:label="us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_639138733436045438" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:label="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_639138733436045438" order="4" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_639138733436045438" order="5" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureInventoriesDetails" xlink:type="extended" xlink:title="99940301 - Disclosure - Inventories (Details)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InventoryDisclosureAbstract" xlink:label="loc_us-gaap_InventoryDisclosureAbstract_217" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InventoryGross" xlink:label="us-gaap_InventoryGross_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_InventoryDisclosureAbstract_217" xlink:to="us-gaap_InventoryGross_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InventoryValuationReserves" xlink:label="us-gaap_InventoryValuationReserves_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_InventoryDisclosureAbstract_217" xlink:to="us-gaap_InventoryValuationReserves_639138733436045438" order="2" use="optional" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InventoryNet" xlink:label="us-gaap_InventoryNet_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_InventoryDisclosureAbstract_217" xlink:to="us-gaap_InventoryNet_639138733436045438" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosurePropertyPlantAndEquipmentPropertyPlantAndEquipmentDetails" xlink:type="extended" xlink:title="99940401 - Disclosure - Property, plant and equipment - Property, plant and equipment (Details)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentAbstract" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAbstract_226" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:label="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAbstract_226" xlink:to="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_639138733436045438" xlink:to="us-gaap_PropertyPlantAndEquipmentByTypeAxis_639138733436045438" order="1" use="optional" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_PropertyPlantAndEquipmentByTypeAxis_639138733436045438" xlink:to="us-gaap_PropertyPlantAndEquipmentTypeDomain_639138733436045438" order="1" use="optional" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LandMember" xlink:label="us-gaap_LandMember_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain_639138733436045438" xlink:to="us-gaap_LandMember_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LandImprovementsMember" xlink:label="us-gaap_LandImprovementsMember_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain_639138733436045438" xlink:to="us-gaap_LandImprovementsMember_639138733436045438" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BuildingMember" xlink:label="us-gaap_BuildingMember_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain_639138733436045438" xlink:to="us-gaap_BuildingMember_639138733436045438" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BuildingImprovementsMember" xlink:label="us-gaap_BuildingImprovementsMember_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain_639138733436045438" xlink:to="us-gaap_BuildingImprovementsMember_639138733436045438" order="4" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_CylindersMember" xlink:label="hdsn_CylindersMember_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain_639138733436045438" xlink:to="hdsn_CylindersMember_639138733436045438" order="5" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquipmentMember" xlink:label="us-gaap_EquipmentMember_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain_639138733436045438" xlink:to="us-gaap_EquipmentMember_639138733436045438" order="6" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsHeldUnderCapitalLeasesMember" xlink:label="us-gaap_AssetsHeldUnderCapitalLeasesMember_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain_639138733436045438" xlink:to="us-gaap_AssetsHeldUnderCapitalLeasesMember_639138733436045438" order="7" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VehiclesMember" xlink:label="us-gaap_VehiclesMember_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain_639138733436045438" xlink:to="us-gaap_VehiclesMember_639138733436045438" order="8" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ComputerEquipmentMember" xlink:label="us-gaap_ComputerEquipmentMember_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain_639138733436045438" xlink:to="us-gaap_ComputerEquipmentMember_639138733436045438" order="9" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FurnitureAndFixturesMember" xlink:label="us-gaap_FurnitureAndFixturesMember_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain_639138733436045438" xlink:to="us-gaap_FurnitureAndFixturesMember_639138733436045438" order="10" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LeaseholdImprovementsMember" xlink:label="us-gaap_LeaseholdImprovementsMember_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain_639138733436045438" xlink:to="us-gaap_LeaseholdImprovementsMember_639138733436045438" order="11" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConstructionInProgressMember" xlink:label="us-gaap_ConstructionInProgressMember_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain_639138733436045438" xlink:to="us-gaap_ConstructionInProgressMember_639138733436045438" order="12" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis" xlink:label="srt_RangeAxis_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_639138733436045438" xlink:to="srt_RangeAxis_639138733436045438" order="2" use="optional" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember" xlink:label="srt_RangeMember_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_RangeAxis_639138733436045438" xlink:to="srt_RangeMember_639138733436045438" order="1" use="optional" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember" xlink:label="srt_MinimumMember_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_RangeMember_639138733436045438" xlink:to="srt_MinimumMember_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember" xlink:label="srt_MaximumMember_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_RangeMember_639138733436045438" xlink:to="srt_MaximumMember_639138733436045438" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="us-gaap_PropertyPlantAndEquipmentLineItems_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_639138733436045438" xlink:to="us-gaap_PropertyPlantAndEquipmentLineItems_639138733436045438" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentGross" xlink:label="us-gaap_PropertyPlantAndEquipmentGross_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems_639138733436045438" xlink:to="us-gaap_PropertyPlantAndEquipmentGross_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:label="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems_639138733436045438" xlink:to="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_639138733436045438" order="2" use="optional" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="us-gaap_PropertyPlantAndEquipmentNet_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems_639138733436045438" xlink:to="us-gaap_PropertyPlantAndEquipmentNet_639138733436045438" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:label="us-gaap_PropertyPlantAndEquipmentUsefulLife_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems_639138733436045438" xlink:to="us-gaap_PropertyPlantAndEquipmentUsefulLife_639138733436045438" order="4" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosurePropertyPlantAndEquipmentAdditionalInformationDetails" xlink:type="extended" xlink:title="99940402 - Disclosure - Property, plant and equipment - Additional Information (Details)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentAbstract" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAbstract_252" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DepreciationDepletionAndAmortization" xlink:label="us-gaap_DepreciationDepletionAndAmortization_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAbstract_252" xlink:to="us-gaap_DepreciationDepletionAndAmortization_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostOfGoodsAndServicesSoldDepreciation" xlink:label="us-gaap_CostOfGoodsAndServicesSoldDepreciation_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAbstract_252" xlink:to="us-gaap_CostOfGoodsAndServicesSoldDepreciation_639138733436045438" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureLeasesAdditionalInformationDetails" xlink:type="extended" xlink:title="99940501 - Disclosure - Leases - Additional Information (Details)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LeasesAbstract" xlink:label="loc_us-gaap_LeasesAbstract_405412" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LesseeOperatingLeaseTermOfContract" xlink:label="us-gaap_LesseeOperatingLeaseTermOfContract_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LeasesAbstract_405412" xlink:to="us-gaap_LesseeOperatingLeaseTermOfContract_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeaseExpense" xlink:label="us-gaap_OperatingLeaseExpense_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LeasesAbstract_405412" xlink:to="us-gaap_OperatingLeaseExpense_639138733436045438" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureLeasesMaturityOfLeasePaymentsDetails" xlink:type="extended" xlink:title="99940502 - Disclosure - Leases - Maturity of lease payments (Details)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LeasesAbstract" xlink:label="loc_us-gaap_LeasesAbstract_405309" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LeasesAbstract_405309" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear_639138733436045438" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_639138733436045438" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LeasesAbstract_405309" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_639138733436045438" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LeasesAbstract_405309" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_639138733436202502" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="6" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LeasesAbstract_405309" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_639138733436202502" order="4" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="6" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LeasesAbstract_405309" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_639138733436202502" order="5" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFour" xlink:label="hdsn_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFour_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LeasesAbstract_405309" xlink:to="hdsn_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFour_639138733436202502" order="6" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="4" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LeasesAbstract_405309" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_639138733436202502" order="7" use="optional" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LeasesAbstract_405309" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_639138733436202502" order="8" use="optional" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" priority="4" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeaseLiability" xlink:label="us-gaap_OperatingLeaseLiability_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LeasesAbstract_405309" xlink:to="us-gaap_OperatingLeaseLiability_639138733436202502" order="9" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureLeasesBalanceSheetAndOtherDetails" xlink:type="extended" xlink:title="99940503 - Disclosure - Leases - Balance Sheet and Other (Details)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LeasesAbstract" xlink:label="loc_us-gaap_LeasesAbstract_405379" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_BalanceSheetClassificationAbstract" xlink:label="hdsn_BalanceSheetClassificationAbstract_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LeasesAbstract_405379" xlink:to="hdsn_BalanceSheetClassificationAbstract_639138733436202502" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeaseLiabilityCurrent" xlink:label="us-gaap_OperatingLeaseLiabilityCurrent_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="hdsn_BalanceSheetClassificationAbstract_639138733436202502" xlink:to="us-gaap_OperatingLeaseLiabilityCurrent_639138733436202502" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeaseLiabilityCurrentStatementOfFinancialPositionExtensibleList" xlink:label="us-gaap_OperatingLeaseLiabilityCurrentStatementOfFinancialPositionExtensibleList_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_OperatingLeaseLiabilityCurrent_639138733436202502" xlink:to="us-gaap_OperatingLeaseLiabilityCurrentStatementOfFinancialPositionExtensibleList_639138733436202502" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:label="us-gaap_OperatingLeaseLiabilityNoncurrent_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="hdsn_BalanceSheetClassificationAbstract_639138733436202502" xlink:to="us-gaap_OperatingLeaseLiabilityNoncurrent_639138733436202502" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeaseLiability" xlink:label="us-gaap_OperatingLeaseLiability_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="hdsn_BalanceSheetClassificationAbstract_639138733436202502" xlink:to="us-gaap_OperatingLeaseLiability_639138733436202502" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1" xlink:label="us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LeasesAbstract_405379" xlink:to="us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_639138733436202502" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent" xlink:label="us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LeasesAbstract_405379" xlink:to="us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_639138733436202502" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureLeasesSupplementalCashFlowDetails" xlink:type="extended" xlink:title="99940504 - Disclosure - Leases - Supplemental cash flow (Details)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LeasesAbstract" xlink:label="us-gaap_LeasesAbstract" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeasePayments" xlink:label="us-gaap_OperatingLeasePayments_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LeasesAbstract" xlink:to="us-gaap_OperatingLeasePayments_639138733436202502" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability" xlink:label="us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LeasesAbstract" xlink:to="us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_639138733436202502" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureGoodwillAndIntangibleAssetsAdditionalInformationDetails" xlink:type="extended" xlink:title="99940601 - Disclosure - Goodwill and intangible assets - Additional Information (Details)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract" xlink:label="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract_281" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillImpairmentLoss" xlink:label="us-gaap_GoodwillImpairmentLoss_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract_281" xlink:to="us-gaap_GoodwillImpairmentLoss_639138733436202502" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Goodwill" xlink:label="us-gaap_Goodwill_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract_281" xlink:to="us-gaap_Goodwill_639138733436202502" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AmortizationOfIntangibleAssets" xlink:label="us-gaap_AmortizationOfIntangibleAssets_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract_281" xlink:to="us-gaap_AmortizationOfIntangibleAssets_639138733436202502" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureGoodwillAndIntangibleAssetsOtherIntangibleAssetsDetails" xlink:type="extended" xlink:title="99940602 - Disclosure - Goodwill and intangible assets - Other intangible assets (Details)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract" xlink:label="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract_259" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:label="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract_259" xlink:to="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_639138733436202502" order="1" use="optional" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_639138733436202502" xlink:to="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_639138733436202502" order="1" use="optional" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_639138733436202502" xlink:to="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_639138733436202502" order="1" use="optional" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NoncompeteAgreementsMember" xlink:label="us-gaap_NoncompeteAgreementsMember_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_639138733436202502" xlink:to="us-gaap_NoncompeteAgreementsMember_639138733436202502" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CustomerRelationshipsMember" xlink:label="us-gaap_CustomerRelationshipsMember_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_639138733436202502" xlink:to="us-gaap_CustomerRelationshipsMember_639138733436202502" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AboveMarketLeasesMember" xlink:label="us-gaap_AboveMarketLeasesMember_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_639138733436202502" xlink:to="us-gaap_AboveMarketLeasesMember_639138733436202502" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TradeNamesMember" xlink:label="us-gaap_TradeNamesMember_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_639138733436202502" xlink:to="us-gaap_TradeNamesMember_639138733436202502" order="4" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis" xlink:label="srt_RangeAxis_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_639138733436202502" xlink:to="srt_RangeAxis_639138733436202502" order="2" use="optional" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember" xlink:label="srt_RangeMember_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_RangeAxis_639138733436202502" xlink:to="srt_RangeMember_639138733436202502" order="1" use="optional" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember" xlink:label="srt_MinimumMember_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_RangeMember_639138733436202502" xlink:to="srt_MinimumMember_639138733436202502" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember" xlink:label="srt_MaximumMember_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_RangeMember_639138733436202502" xlink:to="srt_MaximumMember_639138733436202502" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:label="us-gaap_FiniteLivedIntangibleAssetsLineItems_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_639138733436202502" xlink:to="us-gaap_FiniteLivedIntangibleAssetsLineItems_639138733436202502" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1" xlink:label="us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_FiniteLivedIntangibleAssetsLineItems_639138733436202502" xlink:to="us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1_639138733436202502" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsGross" xlink:label="us-gaap_FiniteLivedIntangibleAssetsGross_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_FiniteLivedIntangibleAssetsLineItems_639138733436202502" xlink:to="us-gaap_FiniteLivedIntangibleAssetsGross_639138733436202502" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_FiniteLivedIntangibleAssetsLineItems_639138733436202502" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_639138733436202502" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsNet" xlink:label="us-gaap_FiniteLivedIntangibleAssetsNet_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_FiniteLivedIntangibleAssetsLineItems_639138733436202502" xlink:to="us-gaap_FiniteLivedIntangibleAssetsNet_639138733436202502" order="4" use="optional" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureShareBasedCompensationDetails" xlink:type="extended" xlink:title="99940701 - Disclosure - Share-Based Compensation (Details)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationAbstract" xlink:label="us-gaap_ShareBasedCompensationAbstract" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:label="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ShareBasedCompensationAbstract" xlink:to="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_639138733436202502" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="us-gaap_IncomeStatementLocationAxis_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_639138733436202502" xlink:to="us-gaap_IncomeStatementLocationAxis_639138733436202502" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="us-gaap_IncomeStatementLocationDomain_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_IncomeStatementLocationAxis_639138733436202502" xlink:to="us-gaap_IncomeStatementLocationDomain_639138733436202502" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember" xlink:label="us-gaap_SellingGeneralAndAdministrativeExpensesMember_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_IncomeStatementLocationDomain_639138733436202502" xlink:to="us-gaap_SellingGeneralAndAdministrativeExpensesMember_639138733436202502" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis" xlink:label="us-gaap_AwardTypeAxis_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_639138733436202502" xlink:to="us-gaap_AwardTypeAxis_639138733436202502" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_AwardTypeAxis_639138733436202502" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_639138733436202502" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="us-gaap_EmployeeStockOptionMember_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_639138733436202502" xlink:to="us-gaap_EmployeeStockOptionMember_639138733436202502" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_IncentiveStockOptionsMember" xlink:label="hdsn_IncentiveStockOptionsMember_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_639138733436202502" xlink:to="hdsn_IncentiveStockOptionsMember_639138733436202502" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockAppreciationRightsSARSMember" xlink:label="us-gaap_StockAppreciationRightsSARSMember_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_639138733436202502" xlink:to="us-gaap_StockAppreciationRightsSARSMember_639138733436202502" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis" xlink:label="srt_RangeAxis_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_639138733436202502" xlink:to="srt_RangeAxis_639138733436202502" order="3" use="optional" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember" xlink:label="srt_RangeMember_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_RangeAxis_639138733436202502" xlink:to="srt_RangeMember_639138733436202502" order="1" use="optional" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember" xlink:label="srt_MinimumMember_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_RangeMember_639138733436202502" xlink:to="srt_MinimumMember_639138733436202502" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember" xlink:label="srt_MaximumMember_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_RangeMember_639138733436202502" xlink:to="srt_MaximumMember_639138733436202502" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameAxis" xlink:label="us-gaap_PlanNameAxis_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_639138733436202502" xlink:to="us-gaap_PlanNameAxis_639138733436202502" order="4" use="optional" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameDomain" xlink:label="us-gaap_PlanNameDomain_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_PlanNameAxis_639138733436202502" xlink:to="us-gaap_PlanNameDomain_639138733436202502" order="1" use="optional" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_TwoThousandAndEighteenStockIncentivePlanMember" xlink:label="hdsn_TwoThousandAndEighteenStockIncentivePlanMember_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_PlanNameDomain_639138733436202502" xlink:to="hdsn_TwoThousandAndEighteenStockIncentivePlanMember_639138733436202502" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_TwoThousandAndTwentyStockIncentivePlanMember" xlink:label="hdsn_TwoThousandAndTwentyStockIncentivePlanMember_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_PlanNameDomain_639138733436202502" xlink:to="hdsn_TwoThousandAndTwentyStockIncentivePlanMember_639138733436202502" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_StockIncentivePlan2024Member" xlink:label="hdsn_StockIncentivePlan2024Member_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_PlanNameDomain_639138733436202502" xlink:to="hdsn_StockIncentivePlan2024Member_639138733436202502" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VestingAxis" xlink:label="us-gaap_VestingAxis_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_639138733436202502" xlink:to="us-gaap_VestingAxis_639138733436202502" order="5" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VestingDomain" xlink:label="us-gaap_VestingDomain_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_VestingAxis_639138733436202502" xlink:to="us-gaap_VestingDomain_639138733436202502" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationAwardTrancheOneMember" xlink:label="us-gaap_ShareBasedCompensationAwardTrancheOneMember_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_VestingDomain_639138733436202502" xlink:to="us-gaap_ShareBasedCompensationAwardTrancheOneMember_639138733436202502" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_VestingOnFirstAnniversaryOfGrantMember" xlink:label="hdsn_VestingOnFirstAnniversaryOfGrantMember_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_VestingDomain_639138733436202502" xlink:to="hdsn_VestingOnFirstAnniversaryOfGrantMember_639138733436202502" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_VestingOnSecondAnniversaryOfGrantMember" xlink:label="hdsn_VestingOnSecondAnniversaryOfGrantMember_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_VestingDomain_639138733436202502" xlink:to="hdsn_VestingOnSecondAnniversaryOfGrantMember_639138733436202502" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_639138733436202502" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_639138733436202502" order="6" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="us-gaap_AllocatedShareBasedCompensationExpense_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_639138733436202502" xlink:to="us-gaap_AllocatedShareBasedCompensationExpense_639138733436202502" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredCompensationArrangementWithIndividualCommonStockReservedForFutureIssuance" xlink:label="us-gaap_DeferredCompensationArrangementWithIndividualCommonStockReservedForFutureIssuance_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_639138733436202502" xlink:to="us-gaap_DeferredCompensationArrangementWithIndividualCommonStockReservedForFutureIssuance_639138733436202502" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_639138733436202502" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_639138733436202502" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="6" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_639138733436202502" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_639138733436202502" order="4" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageFromFairMarketPrice" xlink:label="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageFromFairMarketPrice_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_639138733436202502" xlink:to="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageFromFairMarketPrice_639138733436202502" order="5" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_639138733436202502" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_639138733436202502" order="6" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockCapitalSharesReservedForFutureIssuance" xlink:label="us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_639138733436202502" xlink:to="us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_639138733436202502" order="7" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_639138733436202502" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_639138733436202502" order="8" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_639138733436202502" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares_639138733436202502" order="9" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_639138733436202502" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_639138733436202502" order="10" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_639138733436202502" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares_639138733436202502" order="11" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_639138733436202502" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_639138733436202502" order="12" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAggregateIntrinsicValueNonvested." xlink:label="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAggregateIntrinsicValueNonvested._639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_639138733436202502" xlink:to="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAggregateIntrinsicValueNonvested._639138733436202502" order="13" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_639138733436202502" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_639138733436202502" order="14" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" priority="1" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureShareBasedCompensationSummaryOfActivityForStockOptionsAndStockAppreciationRightsDetails" xlink:type="extended" xlink:title="99940703 - Disclosure - Share-Based Compensation - Summary of the activity for Stock Options and Stock Appreciation Rights (Details)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationAbstract" xlink:label="us-gaap_ShareBasedCompensationAbstract" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:label="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ShareBasedCompensationAbstract" xlink:to="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_639138733436202502" order="1" use="optional" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameAxis" xlink:label="us-gaap_PlanNameAxis_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_639138733436202502" xlink:to="us-gaap_PlanNameAxis_639138733436202502" order="1" use="optional" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameDomain" xlink:label="us-gaap_PlanNameDomain_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_PlanNameAxis_639138733436202502" xlink:to="us-gaap_PlanNameDomain_639138733436202502" order="1" use="optional" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_StockOptionPlanMember" xlink:label="hdsn_StockOptionPlanMember_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_PlanNameDomain_639138733436202502" xlink:to="hdsn_StockOptionPlanMember_639138733436202502" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_639138733436202502" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_639138733436202502" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_639138733436202502" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_639138733436202502" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_639138733436202502" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_639138733436202502" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/periodStartLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_639138733436202502" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_639138733436202502" order="2" use="optional" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:label="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_639138733436202502" xlink:to="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_639138733436202502" order="3" use="optional" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod_639138733436202502" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_639138733436202502" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod_639138733436202502" order="4" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_6391387334362025021" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_639138733436202502" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_6391387334362025021" order="5" use="optional" preferredLabel="http://www.xbrl.org/2003/role/periodEndLabel" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceAbstract" xlink:label="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceAbstract_639138733436360055" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_639138733436202502" xlink:to="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceAbstract_639138733436360055" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_639138733436360055" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceAbstract_639138733436360055" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_639138733436360055" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/periodStartLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_639138733436360055" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceAbstract_639138733436360055" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_639138733436360055" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_639138733436360055" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceAbstract_639138733436360055" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_639138733436360055" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_639138733436360055" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceAbstract_639138733436360055" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_639138733436360055" order="4" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_6391387334363600551" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceAbstract_639138733436360055" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_6391387334363600551" order="5" use="optional" preferredLabel="http://www.xbrl.org/2003/role/periodEndLabel" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureShareBasedCompensationWeightedAverageContractualLifeInYearsAndWeightedAverageExercisePriceDetails" xlink:type="extended" xlink:title="99940704 - Disclosure - Share-Based Compensation - Weighted average contractual life in years and the weighted average exercise price (Details)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationAbstract" xlink:label="us-gaap_ShareBasedCompensationAbstract" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_639138733436365165" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ShareBasedCompensationAbstract" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_639138733436365165" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_639138733436365165" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_639138733436365165" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_639138733436365165" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_639138733436365165" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ShareBasedCompensationAbstract" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_639138733436365165" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1_639138733436365165" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_639138733436365165" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1_639138733436365165" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceAbstract" xlink:label="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceAbstract_639138733436365165" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ShareBasedCompensationAbstract" xlink:to="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceAbstract_639138733436365165" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice_639138733436365165" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceAbstract_639138733436365165" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice_639138733436365165" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureShortTermAndLongTermDebtDetails" xlink:type="extended" xlink:title="99940801 - Disclosure - Short-term and long-term debt (Details)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtDisclosureAbstract" xlink:label="loc_us-gaap_DebtDisclosureAbstract_436" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityTable" xlink:label="us-gaap_LineOfCreditFacilityTable_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtDisclosureAbstract_436" xlink:to="us-gaap_LineOfCreditFacilityTable_639138733436370483" order="1" use="optional" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis" xlink:label="us-gaap_DebtInstrumentAxis_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LineOfCreditFacilityTable_639138733436370483" xlink:to="us-gaap_DebtInstrumentAxis_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="us-gaap_DebtInstrumentNameDomain_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_DebtInstrumentAxis_639138733436370483" xlink:to="us-gaap_DebtInstrumentNameDomain_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_WellsFargoMember" xlink:label="hdsn_WellsFargoMember_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_DebtInstrumentNameDomain_639138733436370483" xlink:to="hdsn_WellsFargoMember_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityAxis" xlink:label="us-gaap_CreditFacilityAxis_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LineOfCreditFacilityTable_639138733436370483" xlink:to="us-gaap_CreditFacilityAxis_639138733436370483" order="2" use="optional" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityDomain" xlink:label="us-gaap_CreditFacilityDomain_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_CreditFacilityAxis_639138733436370483" xlink:to="us-gaap_CreditFacilityDomain_639138733436370483" order="1" use="optional" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_SwingLineLoanMember" xlink:label="hdsn_SwingLineLoanMember_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_CreditFacilityDomain_639138733436370483" xlink:to="hdsn_SwingLineLoanMember_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LetterOfCreditMember" xlink:label="us-gaap_LetterOfCreditMember_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_CreditFacilityDomain_639138733436370483" xlink:to="us-gaap_LetterOfCreditMember_639138733436370483" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevolvingCreditFacilityMember" xlink:label="us-gaap_RevolvingCreditFacilityMember_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_CreditFacilityDomain_639138733436370483" xlink:to="us-gaap_RevolvingCreditFacilityMember_639138733436370483" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_WaiverAndThirdAmendmentToTermLoanCreditAndSecurityAgreementMember" xlink:label="hdsn_WaiverAndThirdAmendmentToTermLoanCreditAndSecurityAgreementMember_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_CreditFacilityDomain_639138733436370483" xlink:to="hdsn_WaiverAndThirdAmendmentToTermLoanCreditAndSecurityAgreementMember_639138733436370483" order="4" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_FourthAmendmentMember" xlink:label="hdsn_FourthAmendmentMember_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_CreditFacilityDomain_639138733436370483" xlink:to="hdsn_FourthAmendmentMember_639138733436370483" order="5" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StatementScenarioAxis" xlink:label="srt_StatementScenarioAxis_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LineOfCreditFacilityTable_639138733436370483" xlink:to="srt_StatementScenarioAxis_639138733436370483" order="3" use="optional" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ScenarioUnspecifiedDomain" xlink:label="srt_ScenarioUnspecifiedDomain_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_StatementScenarioAxis_639138733436370483" xlink:to="srt_ScenarioUnspecifiedDomain_639138733436370483" order="1" use="optional" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_BaseRateLoansMember" xlink:label="hdsn_BaseRateLoansMember_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_ScenarioUnspecifiedDomain_639138733436370483" xlink:to="hdsn_BaseRateLoansMember_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_SofrLoansMember" xlink:label="hdsn_SofrLoansMember_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_ScenarioUnspecifiedDomain_639138733436370483" xlink:to="hdsn_SofrLoansMember_639138733436370483" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VariableRateAxis" xlink:label="us-gaap_VariableRateAxis_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LineOfCreditFacilityTable_639138733436370483" xlink:to="us-gaap_VariableRateAxis_639138733436370483" order="4" use="optional" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VariableRateDomain" xlink:label="us-gaap_VariableRateDomain_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_VariableRateAxis_639138733436370483" xlink:to="us-gaap_VariableRateDomain_639138733436370483" order="1" use="optional" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BaseRateMember" xlink:label="us-gaap_BaseRateMember_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_VariableRateDomain_639138733436370483" xlink:to="us-gaap_BaseRateMember_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_FedFundsRateMember" xlink:label="hdsn_FedFundsRateMember_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_VariableRateDomain_639138733436370483" xlink:to="hdsn_FedFundsRateMember_639138733436370483" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SecuredOvernightFinancingRateSofrMember" xlink:label="us-gaap_SecuredOvernightFinancingRateSofrMember_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_VariableRateDomain_639138733436370483" xlink:to="us-gaap_SecuredOvernightFinancingRateSofrMember_639138733436370483" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_PrimeCommercialLendingRateOfWellsFargoMember" xlink:label="hdsn_PrimeCommercialLendingRateOfWellsFargoMember_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_VariableRateDomain_639138733436370483" xlink:to="hdsn_PrimeCommercialLendingRateOfWellsFargoMember_639138733436370483" order="4" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis" xlink:label="srt_RangeAxis_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LineOfCreditFacilityTable_639138733436370483" xlink:to="srt_RangeAxis_639138733436370483" order="5" use="optional" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember" xlink:label="srt_RangeMember_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_RangeAxis_639138733436370483" xlink:to="srt_RangeMember_639138733436370483" order="1" use="optional" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember" xlink:label="srt_MinimumMember_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_RangeMember_639138733436370483" xlink:to="srt_MinimumMember_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember" xlink:label="srt_MaximumMember_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_RangeMember_639138733436370483" xlink:to="srt_MaximumMember_639138733436370483" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityAxis" xlink:label="us-gaap_LineOfCreditFacilityAxis_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LineOfCreditFacilityTable_639138733436370483" xlink:to="us-gaap_LineOfCreditFacilityAxis_639138733436370483" order="6" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityLenderDomain" xlink:label="us-gaap_LineOfCreditFacilityLenderDomain_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LineOfCreditFacilityAxis_639138733436370483" xlink:to="us-gaap_LineOfCreditFacilityLenderDomain_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_WellsFargoMember" xlink:label="hdsn_WellsFargoMember_6391387334363704831" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LineOfCreditFacilityLenderDomain_639138733436370483" xlink:to="hdsn_WellsFargoMember_6391387334363704831" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortTermDebtTypeAxis" xlink:label="us-gaap_ShortTermDebtTypeAxis_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LineOfCreditFacilityTable_639138733436370483" xlink:to="us-gaap_ShortTermDebtTypeAxis_639138733436370483" order="7" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortTermDebtTypeDomain" xlink:label="us-gaap_ShortTermDebtTypeDomain_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ShortTermDebtTypeAxis_639138733436370483" xlink:to="us-gaap_ShortTermDebtTypeDomain_639138733436370483" order="1" use="optional" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_FCCRMember" xlink:label="hdsn_FCCRMember_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ShortTermDebtTypeDomain_639138733436370483" xlink:to="hdsn_FCCRMember_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityLineItems" xlink:label="us-gaap_LineOfCreditFacilityLineItems_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LineOfCreditFacilityTable_639138733436370483" xlink:to="us-gaap_LineOfCreditFacilityLineItems_639138733436370483" order="8" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromLinesOfCredit" xlink:label="us-gaap_ProceedsFromLinesOfCredit_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LineOfCreditFacilityLineItems_639138733436370483" xlink:to="us-gaap_ProceedsFromLinesOfCredit_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:label="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LineOfCreditFacilityLineItems_639138733436370483" xlink:to="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_639138733436370483" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LettersOfCreditOutstandingAmount" xlink:label="us-gaap_LettersOfCreditOutstandingAmount_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LineOfCreditFacilityLineItems_639138733436370483" xlink:to="us-gaap_LettersOfCreditOutstandingAmount_639138733436370483" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:label="us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LineOfCreditFacilityLineItems_639138733436370483" xlink:to="us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_639138733436370483" order="4" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityCommitmentFeePercentage" xlink:label="us-gaap_LineOfCreditFacilityCommitmentFeePercentage_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LineOfCreditFacilityLineItems_639138733436370483" xlink:to="us-gaap_LineOfCreditFacilityCommitmentFeePercentage_639138733436370483" order="5" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_LineOfCreditFacilityCovenantComplianceMinimumLiquidity" xlink:label="hdsn_LineOfCreditFacilityCovenantComplianceMinimumLiquidity_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LineOfCreditFacilityLineItems_639138733436370483" xlink:to="hdsn_LineOfCreditFacilityCovenantComplianceMinimumLiquidity_639138733436370483" order="6" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_LineOfCreditFacilityCovenantComplianceMinimumLiquidityToBeDerivedFromAvailability" xlink:label="hdsn_LineOfCreditFacilityCovenantComplianceMinimumLiquidityToBeDerivedFromAvailability_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LineOfCreditFacilityLineItems_639138733436370483" xlink:to="hdsn_LineOfCreditFacilityCovenantComplianceMinimumLiquidityToBeDerivedFromAvailability_639138733436370483" order="7" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_MinimumAggregateUndrawnLoanAvailability" xlink:label="hdsn_MinimumAggregateUndrawnLoanAvailability_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LineOfCreditFacilityLineItems_639138733436370483" xlink:to="hdsn_MinimumAggregateUndrawnLoanAvailability_639138733436370483" order="8" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_FixedChargesCoverageRatio" xlink:label="hdsn_FixedChargesCoverageRatio_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LineOfCreditFacilityLineItems_639138733436370483" xlink:to="hdsn_FixedChargesCoverageRatio_639138733436370483" order="9" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_PeriodForFixedChargeCoverageRatio" xlink:label="hdsn_PeriodForFixedChargeCoverageRatio_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LineOfCreditFacilityLineItems_639138733436370483" xlink:to="hdsn_PeriodForFixedChargeCoverageRatio_639138733436370483" order="10" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity" xlink:label="us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LineOfCreditFacilityLineItems_639138733436370483" xlink:to="us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_639138733436370483" order="11" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="us-gaap_DebtInstrumentFaceAmount_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LineOfCreditFacilityLineItems_639138733436370483" xlink:to="us-gaap_DebtInstrumentFaceAmount_639138733436370483" order="12" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_LineOfCreditFacilityCovenantTermsMaximumShareRepurchasePerCalendarYearAmount" xlink:label="hdsn_LineOfCreditFacilityCovenantTermsMaximumShareRepurchasePerCalendarYearAmount_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LineOfCreditFacilityLineItems_639138733436370483" xlink:to="hdsn_LineOfCreditFacilityCovenantTermsMaximumShareRepurchasePerCalendarYearAmount_639138733436370483" order="13" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_LineOfCreditFacilityCovenantTermsMaximumShareRepurchaseOverFacilityTermAmount" xlink:label="hdsn_LineOfCreditFacilityCovenantTermsMaximumShareRepurchaseOverFacilityTermAmount_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LineOfCreditFacilityLineItems_639138733436370483" xlink:to="hdsn_LineOfCreditFacilityCovenantTermsMaximumShareRepurchaseOverFacilityTermAmount_639138733436370483" order="14" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_LineOfCreditFacilityCovenantTermsMaximumShareRepurchasePerCalendarYearAfterYearOneAmount" xlink:label="hdsn_LineOfCreditFacilityCovenantTermsMaximumShareRepurchasePerCalendarYearAfterYearOneAmount_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_LineOfCreditFacilityLineItems_639138733436370483" xlink:to="hdsn_LineOfCreditFacilityCovenantTermsMaximumShareRepurchasePerCalendarYearAfterYearOneAmount_639138733436370483" order="15" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureAccruedExpensesAndOtherCurrentLiabilitiesDetails" xlink:type="extended" xlink:title="99940901 - Disclosure - Accrued expenses and other current liabilities (Details)">
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_AccruedExpensesAndOtherCurrentLiabilitiesAbstract" xlink:label="hdsn_AccruedExpensesAndOtherCurrentLiabilitiesAbstract_3" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccruedLiabilitiesCurrent" xlink:label="us-gaap_AccruedLiabilitiesCurrent_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="hdsn_AccruedExpensesAndOtherCurrentLiabilitiesAbstract_3" xlink:to="us-gaap_AccruedLiabilitiesCurrent_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CustomerRefundLiabilityCurrent" xlink:label="us-gaap_CustomerRefundLiabilityCurrent_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="hdsn_AccruedExpensesAndOtherCurrentLiabilitiesAbstract_3" xlink:to="us-gaap_CustomerRefundLiabilityCurrent_639138733436370483" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_LeaseObligationsCurrent" xlink:label="hdsn_LeaseObligationsCurrent_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="hdsn_AccruedExpensesAndOtherCurrentLiabilitiesAbstract_3" xlink:to="hdsn_LeaseObligationsCurrent_639138733436370483" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherLiabilitiesCurrent" xlink:label="us-gaap_OtherLiabilitiesCurrent_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="hdsn_AccruedExpensesAndOtherCurrentLiabilitiesAbstract_3" xlink:to="us-gaap_OtherLiabilitiesCurrent_639138733436370483" order="4" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_AccruedLiabilitiesAndOtherLiabilitiesCurrent" xlink:label="hdsn_AccruedLiabilitiesAndOtherLiabilitiesCurrent_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="hdsn_AccruedExpensesAndOtherCurrentLiabilitiesAbstract_3" xlink:to="hdsn_AccruedLiabilitiesAndOtherLiabilitiesCurrent_639138733436370483" order="5" use="optional" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" priority="1" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureAcquisitionAssetsAcquiredAndLiabilitiesDetails" xlink:type="extended" xlink:title="99941001 - Disclosure - Acquisition - Assets acquired and liabilities (Details)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationsAbstract" xlink:label="us-gaap_BusinessCombinationsAbstract_2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_BusinessCombinationsAbstract_2" xlink:to="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="us-gaap_BusinessAcquisitionAxis_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_639138733436370483" xlink:to="us-gaap_BusinessAcquisitionAxis_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="us-gaap_BusinessAcquisitionAcquireeDomain_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_BusinessAcquisitionAxis_639138733436370483" xlink:to="us-gaap_BusinessAcquisitionAcquireeDomain_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_UnitedSuppliersOfAmericaIncAndBBJobberServicesIncMember" xlink:label="hdsn_UnitedSuppliersOfAmericaIncAndBBJobberServicesIncMember_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_BusinessAcquisitionAcquireeDomain_639138733436370483" xlink:to="hdsn_UnitedSuppliersOfAmericaIncAndBBJobberServicesIncMember_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_DenverRefrigerantsIncMember" xlink:label="hdsn_DenverRefrigerantsIncMember_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_BusinessAcquisitionAcquireeDomain_639138733436370483" xlink:to="hdsn_DenverRefrigerantsIncMember_639138733436370483" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_639138733436370483" xlink:to="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_639138733436370483" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_639138733436370483" xlink:to="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NoncompeteAgreementsMember" xlink:label="us-gaap_NoncompeteAgreementsMember_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_639138733436370483" xlink:to="us-gaap_NoncompeteAgreementsMember_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CustomerRelationshipsMember" xlink:label="us-gaap_CustomerRelationshipsMember_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_639138733436370483" xlink:to="us-gaap_CustomerRelationshipsMember_639138733436370483" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TradeNamesMember" xlink:label="us-gaap_TradeNamesMember_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_639138733436370483" xlink:to="us-gaap_TradeNamesMember_639138733436370483" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="us-gaap_BusinessAcquisitionLineItems_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_639138733436370483" xlink:to="us-gaap_BusinessAcquisitionLineItems_639138733436370483" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsToAcquireBusinessesGross" xlink:label="us-gaap_PaymentsToAcquireBusinessesGross_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_BusinessAcquisitionLineItems_639138733436370483" xlink:to="us-gaap_PaymentsToAcquireBusinessesGross_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability" xlink:label="us-gaap_BusinessCombinationContingentConsiderationLiability_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_BusinessAcquisitionLineItems_639138733436370483" xlink:to="us-gaap_BusinessCombinationContingentConsiderationLiability_639138733436370483" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationConsiderationTransferred1" xlink:label="us-gaap_BusinessCombinationConsiderationTransferred1_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_BusinessAcquisitionLineItems_639138733436370483" xlink:to="us-gaap_BusinessCombinationConsiderationTransferred1_639138733436370483" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_BusinessAcquisitionLineItems_639138733436370483" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory_639138733436370483" order="4" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_BusinessAcquisitionLineItems_639138733436370483" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_639138733436370483" order="5" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_BusinessAcquisitionLineItems_639138733436370483" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_639138733436370483" order="6" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_BusinessAcquisitionLineItems_639138733436370483" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_639138733436370483" order="7" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Goodwill" xlink:label="us-gaap_Goodwill_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_BusinessAcquisitionLineItems_639138733436370483" xlink:to="us-gaap_Goodwill_639138733436370483" order="8" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife" xlink:label="us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_BusinessAcquisitionLineItems_639138733436370483" xlink:to="us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_639138733436370483" order="9" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_BusinessAcquisitionLineItems_639138733436370483" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_639138733436370483" order="10" use="optional" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" priority="1" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureAcquisitionAdditionalInformationDetails" xlink:type="extended" xlink:title="99941002 - Disclosure - Acquisition - Additional Information (Details)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationsAbstract" xlink:label="us-gaap_BusinessCombinationsAbstract_3" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_BusinessCombinationsAbstract_3" xlink:to="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="us-gaap_BusinessAcquisitionAxis_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_639138733436370483" xlink:to="us-gaap_BusinessAcquisitionAxis_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="us-gaap_BusinessAcquisitionAcquireeDomain_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_BusinessAcquisitionAxis_639138733436370483" xlink:to="us-gaap_BusinessAcquisitionAcquireeDomain_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_DenverRefrigerantsIncMember" xlink:label="hdsn_DenverRefrigerantsIncMember_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_BusinessAcquisitionAcquireeDomain_639138733436370483" xlink:to="hdsn_DenverRefrigerantsIncMember_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis" xlink:label="srt_RangeAxis_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_639138733436370483" xlink:to="srt_RangeAxis_639138733436370483" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember" xlink:label="srt_RangeMember_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_RangeAxis_639138733436370483" xlink:to="srt_RangeMember_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember" xlink:label="srt_MinimumMember_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_RangeMember_639138733436370483" xlink:to="srt_MinimumMember_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember" xlink:label="srt_MaximumMember_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_RangeMember_639138733436370483" xlink:to="srt_MaximumMember_639138733436370483" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="us-gaap_BusinessAcquisitionLineItems_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_639138733436370483" xlink:to="us-gaap_BusinessAcquisitionLineItems_639138733436370483" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsToAcquireBusinessesGross" xlink:label="us-gaap_PaymentsToAcquireBusinessesGross_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_BusinessAcquisitionLineItems_639138733436370483" xlink:to="us-gaap_PaymentsToAcquireBusinessesGross_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability" xlink:label="us-gaap_BusinessCombinationContingentConsiderationLiability_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_BusinessAcquisitionLineItems_639138733436370483" xlink:to="us-gaap_BusinessCombinationContingentConsiderationLiability_639138733436370483" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_BusinessCombinationContingentConsiderationPaymentPeriod" xlink:label="hdsn_BusinessCombinationContingentConsiderationPaymentPeriod_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_BusinessAcquisitionLineItems_639138733436370483" xlink:to="hdsn_BusinessCombinationContingentConsiderationPaymentPeriod_639138733436370483" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationContingentConsiderationLiabilityCurrent" xlink:label="us-gaap_BusinessCombinationContingentConsiderationLiabilityCurrent_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_BusinessAcquisitionLineItems_639138733436370483" xlink:to="us-gaap_BusinessCombinationContingentConsiderationLiabilityCurrent_639138733436370483" order="4" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Goodwill" xlink:label="us-gaap_Goodwill_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_BusinessAcquisitionLineItems_639138733436370483" xlink:to="us-gaap_Goodwill_639138733436370483" order="5" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureShareRepurchasesDetails" xlink:type="extended" xlink:title="99941101 - Disclosure - Share repurchases (Details)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquityNoteAbstract" xlink:label="us-gaap_StockholdersEquityNoteAbstract_1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ShareRepurchaseProgramTable" xlink:label="srt_ShareRepurchaseProgramTable_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StockholdersEquityNoteAbstract_1" xlink:to="srt_ShareRepurchaseProgramTable_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis" xlink:label="srt_RangeAxis_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_ShareRepurchaseProgramTable_639138733436370483" xlink:to="srt_RangeAxis_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember" xlink:label="srt_RangeMember_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_RangeAxis_639138733436370483" xlink:to="srt_RangeMember_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember" xlink:label="srt_MaximumMember_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_RangeMember_639138733436370483" xlink:to="srt_MaximumMember_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StatementScenarioAxis" xlink:label="srt_StatementScenarioAxis_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_ShareRepurchaseProgramTable_639138733436370483" xlink:to="srt_StatementScenarioAxis_639138733436370483" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ScenarioUnspecifiedDomain" xlink:label="srt_ScenarioUnspecifiedDomain_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_StatementScenarioAxis_639138733436370483" xlink:to="srt_ScenarioUnspecifiedDomain_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ScenarioForecastMember" xlink:label="srt_ScenarioForecastMember_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_ScenarioUnspecifiedDomain_639138733436370483" xlink:to="srt_ScenarioForecastMember_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ShareRepurchaseProgramLineItems" xlink:label="srt_ShareRepurchaseProgramLineItems_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_ShareRepurchaseProgramTable_639138733436370483" xlink:to="srt_ShareRepurchaseProgramLineItems_639138733436370483" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StockRepurchaseProgramAuthorizedAmount1" xlink:label="srt_StockRepurchaseProgramAuthorizedAmount1_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_ShareRepurchaseProgramLineItems_639138733436370483" xlink:to="srt_StockRepurchaseProgramAuthorizedAmount1_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_ShareRepurchaseProgramAuthorizedPerCalendarYearAmount" xlink:label="hdsn_ShareRepurchaseProgramAuthorizedPerCalendarYearAmount_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_ShareRepurchaseProgramLineItems_639138733436370483" xlink:to="hdsn_ShareRepurchaseProgramAuthorizedPerCalendarYearAmount_639138733436370483" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodShares" xlink:label="us-gaap_StockRepurchasedAndRetiredDuringPeriodShares_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_ShareRepurchaseProgramLineItems_639138733436370483" xlink:to="us-gaap_StockRepurchasedAndRetiredDuringPeriodShares_639138733436370483" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsForRepurchaseOfCommonStock" xlink:label="us-gaap_PaymentsForRepurchaseOfCommonStock_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_ShareRepurchaseProgramLineItems_639138733436370483" xlink:to="us-gaap_PaymentsForRepurchaseOfCommonStock_639138733436370483" order="4" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockAcquiredAverageCostPerShare" xlink:label="us-gaap_TreasuryStockAcquiredAverageCostPerShare_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="srt_ShareRepurchaseProgramLineItems_639138733436370483" xlink:to="us-gaap_TreasuryStockAcquiredAverageCostPerShare_639138733436370483" order="5" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://www.hudsontech.com/role/DisclosureSegmentInformationDetails" xlink:type="extended" xlink:title="99941201 - Disclosure - Segment information (Details)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingAbstract" xlink:label="us-gaap_SegmentReportingAbstract_2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_SegmentReportingAbstract_2" xlink:to="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="us-gaap_StatementBusinessSegmentsAxis_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_639138733436370483" xlink:to="us-gaap_StatementBusinessSegmentsAxis_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain" xlink:label="us-gaap_SegmentDomain_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_StatementBusinessSegmentsAxis_639138733436370483" xlink:to="us-gaap_SegmentDomain_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/label" />
    <link:loc xlink:type="locator" xlink:href="hdsn-20260331.xsd#hdsn_SingleReportingSegmentMember" xlink:label="hdsn_SingleReportingSegmentMember_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_SegmentDomain_639138733436370483" xlink:to="hdsn_SingleReportingSegmentMember_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="us-gaap_SegmentReportingInformationLineItems_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_639138733436370483" xlink:to="us-gaap_SegmentReportingInformationLineItems_639138733436370483" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NumberOfOperatingSegments" xlink:label="us-gaap_NumberOfOperatingSegments_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_SegmentReportingInformationLineItems_639138733436370483" xlink:to="us-gaap_NumberOfOperatingSegments_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NumberOfReportableSegments" xlink:label="us-gaap_NumberOfReportableSegments_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_SegmentReportingInformationLineItems_639138733436370483" xlink:to="us-gaap_NumberOfReportableSegments_639138733436370483" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax" xlink:label="us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_SegmentReportingInformationLineItems_639138733436370483" xlink:to="us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax_639138733436370483" order="3" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostOfGoodsAndServicesSoldAbstract" xlink:label="us-gaap_CostOfGoodsAndServicesSoldAbstract_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_SegmentReportingInformationLineItems_639138733436370483" xlink:to="us-gaap_CostOfGoodsAndServicesSoldAbstract_639138733436370483" order="4" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostDirectMaterial" xlink:label="us-gaap_CostDirectMaterial_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_CostOfGoodsAndServicesSoldAbstract_639138733436370483" xlink:to="us-gaap_CostDirectMaterial_639138733436370483" order="1" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostDirectLabor" xlink:label="us-gaap_CostDirectLabor_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_CostOfGoodsAndServicesSoldAbstract_639138733436370483" xlink:to="us-gaap_CostDirectLabor_639138733436370483" order="2" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestIncomeExpenseNonoperatingNet" xlink:label="us-gaap_InterestIncomeExpenseNonoperatingNet_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_CostOfGoodsAndServicesSoldAbstract_639138733436370483" xlink:to="us-gaap_InterestIncomeExpenseNonoperatingNet_639138733436370483" order="3" use="optional" preferredLabel="http://www.xbrl.org/2009/role/negatedTerseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DepreciationAndAmortization" xlink:label="us-gaap_DepreciationAndAmortization_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_CostOfGoodsAndServicesSoldAbstract_639138733436370483" xlink:to="us-gaap_DepreciationAndAmortization_639138733436370483" order="4" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProfessionalFees" xlink:label="us-gaap_ProfessionalFees_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_CostOfGoodsAndServicesSoldAbstract_639138733436370483" xlink:to="us-gaap_ProfessionalFees_639138733436370483" order="5" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingOtherItemAmount" xlink:label="us-gaap_SegmentReportingOtherItemAmount_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_CostOfGoodsAndServicesSoldAbstract_639138733436370483" xlink:to="us-gaap_SegmentReportingOtherItemAmount_639138733436370483" order="6" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="us-gaap_IncomeTaxExpenseBenefit_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_CostOfGoodsAndServicesSoldAbstract_639138733436370483" xlink:to="us-gaap_IncomeTaxExpenseBenefit_639138733436370483" order="7" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss" xlink:label="us-gaap_NetIncomeLoss_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_SegmentReportingInformationLineItems_639138733436370483" xlink:to="us-gaap_NetIncomeLoss_639138733436370483" order="5" use="optional" preferredLabel="http://www.xbrl.org/2003/role/totalLabel" priority="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingOtherItemCompositionDescription" xlink:label="us-gaap_SegmentReportingOtherItemCompositionDescription_639138733436370483" />
    <link:presentationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="us-gaap_SegmentReportingInformationLineItems_639138733436370483" xlink:to="us-gaap_SegmentReportingOtherItemCompositionDescription_639138733436370483" order="6" use="optional" preferredLabel="http://www.xbrl.org/2003/role/terseLabel" priority="1" />
  </link:presentationLink>
  <link:presentationLink xlink:role="http://xbrl.sec.gov/ecd/role/InsiderTradingArrangements" xlink:type="extended" xlink:title="995445 - Disclosure - Insider Trading Arrangements" />
</link:linkbase>
