<?xml version="1.0" encoding="utf-8"?>
<!--XBRL document created with Toppan Merrill Bridge  11.4.0.1 -->
<!--Based on XBRL 2.1-->
<!--Created on: 8/6/2026 3:22:42 PM-->
<!--Modified on: 8/6/2026 3:22:42 PM-->
<xsd:schema attributeFormDefault="unqualified" elementFormDefault="qualified" targetNamespace="http://www.oldsecond.com/20260630" xmlns:attributeFormDefault="unqualified" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:net="http://www.xbrl.org/2009/role/net" xmlns:ref="http://www.xbrl.org/2006/ref" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xbrli="http://www.xbrl.org/2003/instance" xmlns:xl="http://www.xbrl.org/2003/XLink" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:us-gaap="http://fasb.org/us-gaap/2024" xmlns:us-roles="http://fasb.org/us-roles/2024" xmlns:negated="http://www.xbrl.org/2009/role/negated" xmlns:dtr-types="http://www.xbrl.org/dtr/type/2022-03-31" xmlns:osbc="http://www.oldsecond.com/20260630" xmlns:enum2="http://xbrl.org/2020/extensible-enumerations-2.0" xmlns:deprecated="http://www.xbrl.org/2009/role/deprecated" xmlns:utr="http://www.xbrl.org/2009/utr" xmlns:dei="http://xbrl.sec.gov/dei/2024" xmlns:srt="http://fasb.org/srt/2024" xmlns:dtr="http://www.xbrl.org/2009/dtr" xmlns:xbrldi="http://xbrl.org/2006/xbrldi" xmlns:ecd="http://xbrl.sec.gov/ecd/2024" xmlns:ecd-sub="http://xbrl.sec.gov/ecd-sub/2024">
  <xsd:annotation>
    <xsd:appinfo>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureStandardAndCustomAxisDomainDefaults" id="DisclosureStandardAndCustomAxisDomainDefaults">
        <link:definition>99900 - Disclosure - Standard And Custom Axis Domain Defaults</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/StatementConsolidatedBalanceSheets" id="StatementConsolidatedBalanceSheets">
        <link:definition>995200100 - Statement - Consolidated Balance Sheets</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/StatementConsolidatedStatementsOfIncome" id="StatementConsolidatedStatementsOfIncome">
        <link:definition>995200200 - Statement - Consolidated Statements of Income</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/StatementConsolidatedStatementsOfComprehensiveIncome" id="StatementConsolidatedStatementsOfComprehensiveIncome">
        <link:definition>995200300 - Statement - Consolidated Statements of Comprehensive Income</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/StatementConsolidatedStatementsOfCashFlows" id="StatementConsolidatedStatementsOfCashFlows">
        <link:definition>995200400 - Statement - Consolidated Statements of Cash Flows</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureAcquisitionBancorpFinancialAssetsAcquiredAndLiabilitiesAssumedDetails" id="DisclosureAcquisitionBancorpFinancialAssetsAcquiredAndLiabilitiesAssumedDetails">
        <link:definition>99940202 - Disclosure - Acquisition - Bancorp Financial assets acquired and liabilities assumed (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureAcquisitionBancorpFinancialScheduleOfPurchasePriceOfLoansAtAcquisitionDetails" id="DisclosureAcquisitionBancorpFinancialScheduleOfPurchasePriceOfLoansAtAcquisitionDetails">
        <link:definition>99940203 - Disclosure - Acquisition - Bancorp Financial - Schedule of Purchase price of loans at acquisition (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureSecuritiesContractualMaturitiesDetails" id="DisclosureSecuritiesContractualMaturitiesDetails">
        <link:definition>99940302 - Disclosure - Securities - Contractual Maturities (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureSecuritiesUnrealizedLossPositionsDetails" id="DisclosureSecuritiesUnrealizedLossPositionsDetails">
        <link:definition>99940303 - Disclosure - Securities - Unrealized Loss Positions (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureLoansAndAllowanceForCreditLossesOnLoansCreditQualityDetails" id="DisclosureLoansAndAllowanceForCreditLossesOnLoansCreditQualityDetails">
        <link:definition>99940407 - Disclosure - Loans and Allowance for Credit Losses on Loans - Credit Quality (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureOtherRealEstateOwnedDetails" id="DisclosureOtherRealEstateOwnedDetails">
        <link:definition>99940501 - Disclosure - Other Real Estate Owned (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureDepositsClassificationsOfDepositsDetails" id="DisclosureDepositsClassificationsOfDepositsDetails">
        <link:definition>99940601 - Disclosure - Deposits - Classifications of Deposits (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureFairValueMeasurementsRecurringDetails" id="DisclosureFairValueMeasurementsRecurringDetails">
        <link:definition>99941202 - Disclosure - Fair Value Measurements - Recurring (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DocumentDocumentAndEntityInformation" id="DocumentDocumentAndEntityInformation">
        <link:definition>995200090 - Document - Document and Entity Information</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/StatementConsolidatedBalanceSheetsParenthetical" id="StatementConsolidatedBalanceSheetsParenthetical">
        <link:definition>995200105 - Statement - Consolidated Balance Sheets (Parenthetical)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/StatementConsolidatedStatementsOfChangesInStockholdersEquity" id="StatementConsolidatedStatementsOfChangesInStockholdersEquity">
        <link:definition>995200500 - Statement - Consolidated Statements of Changes in Stockholders' Equity</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/StatementConsolidatedStatementsOfChangesInStockholdersEquityParenthetical" id="StatementConsolidatedStatementsOfChangesInStockholdersEquityParenthetical">
        <link:definition>995200505 - Statement - Consolidated Statements of Changes in Stockholders' Equity (Parenthetical)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureBasisOfPresentationAndChangesInSignificantAccountingPolicies" id="DisclosureBasisOfPresentationAndChangesInSignificantAccountingPolicies">
        <link:definition>995210101 - Disclosure - Basis of Presentation and Changes in Significant Accounting Policies</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureAcquisition" id="DisclosureAcquisition">
        <link:definition>995210201 - Disclosure - Acquisition</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureSecurities" id="DisclosureSecurities">
        <link:definition>995210301 - Disclosure - Securities</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureLoansAndAllowanceForCreditLossesOnLoans" id="DisclosureLoansAndAllowanceForCreditLossesOnLoans">
        <link:definition>995210401 - Disclosure - Loans and Allowance for Credit Losses on Loans</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureOtherRealEstateOwned" id="DisclosureOtherRealEstateOwned">
        <link:definition>995210501 - Disclosure - Other Real Estate Owned</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureDeposits" id="DisclosureDeposits">
        <link:definition>995210601 - Disclosure - Deposits</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureBorrowings" id="DisclosureBorrowings">
        <link:definition>995210701 - Disclosure - Borrowings</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureJuniorSubordinatedDebentures" id="DisclosureJuniorSubordinatedDebentures">
        <link:definition>995210801 - Disclosure - Junior Subordinated Debentures</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureEquityCompensationPlans" id="DisclosureEquityCompensationPlans">
        <link:definition>995210901 - Disclosure - Equity Compensation Plans</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureEarningsPerShare" id="DisclosureEarningsPerShare">
        <link:definition>995211001 - Disclosure - Earnings Per Share</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureRegulatoryCapitalMatters" id="DisclosureRegulatoryCapitalMatters">
        <link:definition>995211101 - Disclosure - Regulatory &amp; Capital Matters</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureFairValueMeasurements" id="DisclosureFairValueMeasurements">
        <link:definition>995211201 - Disclosure - Fair Value Measurements</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureFairValuesOfFinancialInstruments" id="DisclosureFairValuesOfFinancialInstruments">
        <link:definition>995211301 - Disclosure - Fair Values of Financial Instruments</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureDerivativesHedgingActivitiesAndFinancialInstrumentsWithOffBalanceSheetRisk" id="DisclosureDerivativesHedgingActivitiesAndFinancialInstrumentsWithOffBalanceSheetRisk">
        <link:definition>995211401 - Disclosure - Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureBasisOfPresentationAndChangesInSignificantAccountingPoliciesPolicies" id="DisclosureBasisOfPresentationAndChangesInSignificantAccountingPoliciesPolicies">
        <link:definition>99920102 - Disclosure - Basis of Presentation and Changes in Significant Accounting Policies (Policies)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureAcquisitionTables" id="DisclosureAcquisitionTables">
        <link:definition>99930203 - Disclosure - Acquisition (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureSecuritiesTables" id="DisclosureSecuritiesTables">
        <link:definition>99930303 - Disclosure - Securities (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureLoansAndAllowanceForCreditLossesOnLoansTables" id="DisclosureLoansAndAllowanceForCreditLossesOnLoansTables">
        <link:definition>99930403 - Disclosure - Loans and Allowance for Credit Losses on Loans (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureOtherRealEstateOwnedTables" id="DisclosureOtherRealEstateOwnedTables">
        <link:definition>99930503 - Disclosure - Other Real Estate Owned (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureDepositsTables" id="DisclosureDepositsTables">
        <link:definition>99930603 - Disclosure - Deposits (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureBorrowingsTables" id="DisclosureBorrowingsTables">
        <link:definition>99930703 - Disclosure - Borrowings (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureEquityCompensationPlansTables" id="DisclosureEquityCompensationPlansTables">
        <link:definition>99930903 - Disclosure - Equity Compensation Plans (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureEarningsPerShareTables" id="DisclosureEarningsPerShareTables">
        <link:definition>99931003 - Disclosure - Earnings Per Share (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureRegulatoryCapitalMattersTables" id="DisclosureRegulatoryCapitalMattersTables">
        <link:definition>99931103 - Disclosure - Regulatory &amp; Capital Matters (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureFairValueMeasurementsTables" id="DisclosureFairValueMeasurementsTables">
        <link:definition>99931203 - Disclosure - Fair Value Measurements (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureFairValuesOfFinancialInstrumentsTables" id="DisclosureFairValuesOfFinancialInstrumentsTables">
        <link:definition>99931303 - Disclosure - Fair Values of Financial Instruments (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureDerivativesHedgingActivitiesAndFinancialInstrumentsWithOffBalanceSheetRiskTables" id="DisclosureDerivativesHedgingActivitiesAndFinancialInstrumentsWithOffBalanceSheetRiskTables">
        <link:definition>99931403 - Disclosure - Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureBasisOfPresentationAndChangesInSignificantAccountingPoliciesDetails" id="DisclosureBasisOfPresentationAndChangesInSignificantAccountingPoliciesDetails">
        <link:definition>99940101 - Disclosure - Basis of Presentation and Changes in Significant Accounting Policies (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureAcquisitionDetails" id="DisclosureAcquisitionDetails">
        <link:definition>99940201 - Disclosure - Acquisition (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureSecuritiesAmortizedCostAndFairValueDetails" id="DisclosureSecuritiesAmortizedCostAndFairValueDetails">
        <link:definition>99940301 - Disclosure - Securities - Amortized Cost and Fair Value (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureLoansAndAllowanceForCreditLossesOnLoansMajorClassificationsDetails" id="DisclosureLoansAndAllowanceForCreditLossesOnLoansMajorClassificationsDetails">
        <link:definition>99940401 - Disclosure - Loans and Allowance for Credit Losses on Loans - Major Classifications (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureLoansAndAllowanceForCreditLossesOnLoansMajorClassificationsLoanConcentrationsDetails" id="DisclosureLoansAndAllowanceForCreditLossesOnLoansMajorClassificationsLoanConcentrationsDetails">
        <link:definition>99940402 - Disclosure - Loans and Allowance for Credit Losses on Loans - Major Classifications - Loan Concentrations (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureLoansAndAllowanceForCreditLossesOnLoansDetails" id="DisclosureLoansAndAllowanceForCreditLossesOnLoansDetails">
        <link:definition>99940403 - Disclosure - Loans and Allowance for Credit Losses on Loans (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureLoansAndAllowanceForCreditLossesOnLoansCollateralDependentLoansDetails" id="DisclosureLoansAndAllowanceForCreditLossesOnLoansCollateralDependentLoansDetails">
        <link:definition>99940404 - Disclosure - Loans and Allowance for Credit Losses on Loans - Collateral dependent loans (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureLoansAndAllowanceForCreditLossesOnLoansAgingAnalysisDetails" id="DisclosureLoansAndAllowanceForCreditLossesOnLoansAgingAnalysisDetails">
        <link:definition>99940405 - Disclosure - Loans and Allowance for Credit Losses on Loans - Aging Analysis (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureLoansAndAllowanceForCreditLossesOnLoansNonaccrualsDetails" id="DisclosureLoansAndAllowanceForCreditLossesOnLoansNonaccrualsDetails">
        <link:definition>99940406 - Disclosure - Loans and Allowance for Credit Losses on Loans - Nonaccruals (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureLoansAndAllowanceForCreditLossesOnLoansChargeOffsActivityByLoanTypeDetails" id="DisclosureLoansAndAllowanceForCreditLossesOnLoansChargeOffsActivityByLoanTypeDetails">
        <link:definition>99940408 - Disclosure - Loans and Allowance for Credit Losses on Loans - Charge-offs Activity by Loan Type (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureLoansAndAllowanceForCreditLossesOnLoansLoanModificationsDetails" id="DisclosureLoansAndAllowanceForCreditLossesOnLoansLoanModificationsDetails">
        <link:definition>99940409 - Disclosure - Loans and Allowance for Credit Losses on Loans - Loan Modifications (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureBorrowingsSummaryDetails" id="DisclosureBorrowingsSummaryDetails">
        <link:definition>99940701 - Disclosure - Borrowings - Summary (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureBorrowingsAdditionalInformationDetails" id="DisclosureBorrowingsAdditionalInformationDetails">
        <link:definition>99940702 - Disclosure - Borrowings - Additional information (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureJuniorSubordinatedDebenturesIssuanceDetails" id="DisclosureJuniorSubordinatedDebenturesIssuanceDetails">
        <link:definition>99940801 - Disclosure - Junior Subordinated Debentures - Issuance (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureEquityCompensationPlansDetails" id="DisclosureEquityCompensationPlansDetails">
        <link:definition>99940901 - Disclosure - Equity Compensation Plans (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureEquityCompensationPlansRestrictedStockAndRsusDetails" id="DisclosureEquityCompensationPlansRestrictedStockAndRsusDetails">
        <link:definition>99940902 - Disclosure - Equity Compensation Plans - Restricted Stock and RSUs (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureEarningsPerShareReconciliationDetails" id="DisclosureEarningsPerShareReconciliationDetails">
        <link:definition>99941001 - Disclosure - Earnings Per Share - Reconciliation (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureRegulatoryCapitalMattersDetails" id="DisclosureRegulatoryCapitalMattersDetails">
        <link:definition>99941101 - Disclosure - Regulatory &amp; Capital Matters (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureRegulatoryCapitalMattersCapitalLevelsAndIndustryDefinedRegulatoryMinimumsDetails" id="DisclosureRegulatoryCapitalMattersCapitalLevelsAndIndustryDefinedRegulatoryMinimumsDetails">
        <link:definition>99941102 - Disclosure - Regulatory &amp; Capital Matters - Capital Levels and Industry Defined Regulatory Minimums (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureRegulatoryCapitalMattersDividendRestrictionsDetails" id="DisclosureRegulatoryCapitalMattersDividendRestrictionsDetails">
        <link:definition>99941103 - Disclosure - Regulatory &amp; Capital Matters - Dividend Restrictions (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureFairValueMeasurementsDetails" id="DisclosureFairValueMeasurementsDetails">
        <link:definition>99941201 - Disclosure - Fair Value Measurements (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureFairValueMeasurementsChangesInLevel3Details" id="DisclosureFairValueMeasurementsChangesInLevel3Details">
        <link:definition>99941203 - Disclosure - Fair Value Measurements - Changes in Level 3 (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureFairValueMeasurementsQuantitativeAndQualitativeInformationDetails" id="DisclosureFairValueMeasurementsQuantitativeAndQualitativeInformationDetails">
        <link:definition>99941204 - Disclosure - Fair Value Measurements - Quantitative and Qualitative Information (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureFairValueMeasurementsNonrecurringDetails" id="DisclosureFairValueMeasurementsNonrecurringDetails">
        <link:definition>99941205 - Disclosure - Fair Value Measurements - Nonrecurring (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureFairValuesOfFinancialInstrumentsDetails" id="DisclosureFairValuesOfFinancialInstrumentsDetails">
        <link:definition>99941301 - Disclosure - Fair Values of Financial Instruments (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureDerivativesHedgingActivitiesAndFinancialInstrumentsWithOffBalanceSheetRiskDetails" id="DisclosureDerivativesHedgingActivitiesAndFinancialInstrumentsWithOffBalanceSheetRiskDetails">
        <link:definition>99941401 - Disclosure - Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureDerivativesHedgingActivitiesAndFinancialInstrumentsWithOffBalanceSheetRiskEffectOfFairValueAndCashFlowHedgeAccountingDetails" id="DisclosureDerivativesHedgingActivitiesAndFinancialInstrumentsWithOffBalanceSheetRiskEffectOfFairValueAndCashFlowHedgeAccountingDetails">
        <link:definition>99941402 - Disclosure - Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk - Effect of Fair Value and Cash Flow Hedge Accounting (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureDerivativesHedgingActivitiesAndFinancialInstrumentsWithOffBalanceSheetRiskCommitmentsDetails" id="DisclosureDerivativesHedgingActivitiesAndFinancialInstrumentsWithOffBalanceSheetRiskCommitmentsDetails">
        <link:definition>99941403 - Disclosure - Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk - Commitments (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureSegmentInformation" id="DisclosureSegmentInformation">
        <link:definition>995211501 - Disclosure - Segment Information</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.oldsecond.com/role/DisclosureSegmentInformationDetails" id="DisclosureSegmentInformationDetails">
        <link:definition>99941501 - Disclosure - Segment Information (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="osbc-20260630_pre.xml" xlink:role="http://www.xbrl.org/2003/role/presentationLinkbaseRef" xlink:type="simple" />
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="osbc-20260630_cal.xml" xlink:role="http://www.xbrl.org/2003/role/calculationLinkbaseRef" xlink:type="simple" />
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="osbc-20260630_def.xml" xlink:role="http://www.xbrl.org/2003/role/definitionLinkbaseRef" xlink:type="simple" />
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="osbc-20260630_lab.xml" xlink:role="http://www.xbrl.org/2003/role/labelLinkbaseRef" xlink:type="simple" />
    </xsd:appinfo>
  </xsd:annotation>
  <xsd:import namespace="https://xbrl.org/2023/calculation-1.1" schemaLocation="https://www.xbrl.org/2023/calculation-1.1.xsd" />
  <xsd:import namespace="http://xbrl.sec.gov/ecd/2024" schemaLocation="https://xbrl.sec.gov/ecd/2024/ecd-2024.xsd" />
  <xsd:import namespace="http://xbrl.sec.gov/dei/2024" schemaLocation="https://xbrl.sec.gov/dei/2024/dei-2024.xsd" />
  <xsd:import namespace="http://www.xbrl.org/2009/role/negated" schemaLocation="http://www.xbrl.org/lrr/role/negated-2009-12-16.xsd" />
  <xsd:import namespace="http://www.xbrl.org/dtr/type/2022-03-31" schemaLocation="https://www.xbrl.org/dtr/type/2022-03-31/types.xsd" />
  <xsd:import namespace="http://www.xbrl.org/2003/instance" schemaLocation="http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd" />
  <xsd:import namespace="http://xbrl.org/2005/xbrldt" schemaLocation="http://www.xbrl.org/2005/xbrldt-2005.xsd" />
  <xsd:import namespace="http://fasb.org/us-roles/2024" schemaLocation="https://xbrl.fasb.org/us-gaap/2024/elts/us-roles-2024.xsd" />
  <xsd:import namespace="http://www.xbrl.org/2009/role/net" schemaLocation="http://www.xbrl.org/lrr/role/net-2009-12-16.xsd" />
  <xsd:import namespace="http://fasb.org/us-gaap/2024" schemaLocation="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd" />
  <xsd:import namespace="http://fasb.org/srt/2024" schemaLocation="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd" />
  <xsd:import namespace="http://xbrl.sec.gov/ecd-sub/2024" schemaLocation="https://xbrl.sec.gov/ecd/2024/ecd-sub-2024.xsd" />
  <xsd:element name="FinancingReceivableAllowanceForCreditLossIncrementalWriteoff" id="osbc_FinancingReceivableAllowanceForCreditLossIncrementalWriteoff" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element abstract="false" id="osbc_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCostWeightedAverageYield" name="AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCostWeightedAverageYield" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:percentItemType" xbrli:periodType="duration" />
  <xsd:element abstract="false" id="osbc_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCostWeightedAverageYield" name="AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCostWeightedAverageYield" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:percentItemType" xbrli:periodType="duration" />
  <xsd:element abstract="false" id="osbc_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCostWeightedAverageYield" name="AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCostWeightedAverageYield" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:percentItemType" xbrli:periodType="duration" />
  <xsd:element abstract="false" id="osbc_CardInterchangeIncomeDebit" name="CardInterchangeIncomeDebit" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="osbc_DebitCardInterchangeExpense" name="DebitCardInterchangeExpense" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="osbc_OtherRealEstateOwnedExpense" name="OtherRealEstateOwnedExpense" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="osbc_IncreaseDecreaseInAccruedInterestReceivableAndOtherAssets" name="IncreaseDecreaseInAccruedInterestReceivableAndOtherAssets" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="credit" />
  <xsd:element abstract="false" id="osbc_IncreaseDecreaseInAccruedInterestPayableAndOtherLiabilities" name="IncreaseDecreaseInAccruedInterestPayableAndOtherLiabilities" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="osbc_LoansDisclosureAbstract" name="LoansDisclosureAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element id="osbc_LoansTextBlock" name="LoansTextBlock" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="osbc_AllowanceForLoanLossesDisclosureAbstract" name="AllowanceForLoanLossesDisclosureAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="osbc_FairValuesOfFinancialInstrumentsDisclosureAbstract" name="FairValuesOfFinancialInstrumentsDisclosureAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element id="osbc_FairValuesOfFinancialInstrumentsDisclosureTextBlock" name="FairValuesOfFinancialInstrumentsDisclosureTextBlock" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="osbc_DocumentAndEntityInformationAbstract" name="DocumentAndEntityInformationAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element id="osbc_OtherRealEstateValuationAllowanceRollForwardTableTextBlock" name="OtherRealEstateValuationAllowanceRollForwardTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element id="osbc_OtherRealEstateExpensesRelatedToForeclosedAssetsTableTextBlock" name="OtherRealEstateExpensesRelatedToForeclosedAssetsTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element id="osbc_ForeclosedRealEstateExpenseNetOfLeaseRevenue" name="ForeclosedRealEstateExpenseNetOfLeaseRevenue" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="debit" />
  <xsd:element abstract="true" id="osbc_OtherRealEstateOwnedExpensesRelatedToForeclosedAssetsAbstract" name="OtherRealEstateOwnedExpensesRelatedToForeclosedAssetsAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element id="osbc_ScheduleOfDepositsTableTextBlock" name="ScheduleOfDepositsTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="osbc_MortgageBackedSecuritiesIssuedByUSGovernmentAgenciesMember" name="MortgageBackedSecuritiesIssuedByUSGovernmentAgenciesMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="osbc_AvailableForSaleDebtMaturitiesBeforeSecuritiesWithoutSingleMaturityDateAmortizedCostBasis" name="AvailableForSaleDebtMaturitiesBeforeSecuritiesWithoutSingleMaturityDateAmortizedCostBasis" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element id="osbc_AvailableForSaleDebtMaturitiesBeforeSecuritiesWithoutSingleMaturityDateWeightedAverageYield" name="AvailableForSaleDebtMaturitiesBeforeSecuritiesWithoutSingleMaturityDateWeightedAverageYield" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="osbc_AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateWeightedAverageYield" name="AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateWeightedAverageYield" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="osbc_AvailableForSaleSecuritiesWeightedAverageYield" name="AvailableForSaleSecuritiesWeightedAverageYield" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="osbc_AvailableForSaleDebtMaturitiesBeforeSecuritiesWithoutSingleMaturityDateFairValue" name="AvailableForSaleDebtMaturitiesBeforeSecuritiesWithoutSingleMaturityDateFairValue" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element id="osbc_AvailableForSaleSecuritiesInUnrealizedLossPositionLessThan12MonthsQualitativeDisclosureNumberOfPositions" name="AvailableForSaleSecuritiesInUnrealizedLossPositionLessThan12MonthsQualitativeDisclosureNumberOfPositions" nillable="true" substitutionGroup="xbrli:item" type="xbrli:decimalItemType" xbrli:periodType="instant" />
  <xsd:element id="osbc_AvailableForSaleSecuritiesInUnrealizedLossPositions12MonthsOrLongerQualitativeDisclosureNumberOfPositions" name="AvailableForSaleSecuritiesInUnrealizedLossPositions12MonthsOrLongerQualitativeDisclosureNumberOfPositions" nillable="true" substitutionGroup="xbrli:item" type="xbrli:decimalItemType" xbrli:periodType="instant" />
  <xsd:element id="osbc_ThresholdForDisclosurePercentageOfStockholdersEquity" name="ThresholdForDisclosurePercentageOfStockholdersEquity" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="osbc_FederalHomeLoanBankAdvancesAsPercentageOfTotalAssets" name="FederalHomeLoanBankAdvancesAsPercentageOfTotalAssets" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:percentItemType" xbrli:periodType="instant" />
  <xsd:element id="osbc_IncreaseInTierOneLeverageCapital" name="IncreaseInTierOneLeverageCapital" nillable="true" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" />
  <xsd:element id="osbc_IncreaseInCapitalToRiskWeightedAssetsRatio" name="IncreaseInCapitalToRiskWeightedAssetsRatio" nillable="true" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="osbc_CapitalToRiskBasedRatiosAbstract" name="CapitalToRiskBasedRatiosAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="osbc_DividendRestrictionsAndDeferralsAbstract" name="DividendRestrictionsAndDeferralsAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element id="osbc_DividendRestrictionsNumberOfPreviousYearsRetainedProfit" name="DividendRestrictionsNumberOfPreviousYearsRetainedProfit" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="osbc_DerivativeCommitmentsMember" name="DerivativeCommitmentsMember" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element id="osbc_CommitmentsToExtendCreditToBorrowersMember" name="CommitmentsToExtendCreditToBorrowersMember" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element id="osbc_TrustPreferredSecuritiesIssuanceCostAmortizationPeriod" name="TrustPreferredSecuritiesIssuanceCostAmortizationPeriod" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="osbc_TrustPreferredSecuritiesMaturityPeriod" name="TrustPreferredSecuritiesMaturityPeriod" nillable="true" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" />
  <xsd:element id="osbc_TrustPreferredSecuritiesCashDistributionFixedRatePercentage" name="TrustPreferredSecuritiesCashDistributionFixedRatePercentage" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="osbc_TrustPreferredSecuritiesBasisSpreadOnVariableRate" name="TrustPreferredSecuritiesBasisSpreadOnVariableRate" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="osbc_TrustPreferredSecuritiesDescriptionOfVariableRateBasis" name="TrustPreferredSecuritiesDescriptionOfVariableRateBasis" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="osbc_OldSecondCapitalTrustIIMember" name="OldSecondCapitalTrustIIMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="osbc_LoansAndLeasesReceivableAsPercentageOfAggregatePortfolio" name="LoansAndLeasesReceivableAsPercentageOfAggregatePortfolio" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:percentItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="osbc_RestrictedStockAndRestrictedStockUnitsMember" name="RestrictedStockAndRestrictedStockUnitsMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="osbc_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTableTextBlock" name="ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="osbc_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable" name="FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable" nillable="true" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="osbc_MortgageServicingRightsMember" name="MortgageServicingRightsMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="osbc_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems" name="FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="osbc_ScheduleOfEarningsPerShareBasicAndDilutedTable" name="ScheduleOfEarningsPerShareBasicAndDilutedTable" nillable="true" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="osbc_EarningsPerShareBasicAndDilutedLineItems" name="EarningsPerShareBasicAndDilutedLineItems" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="osbc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossAbstract" name="FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="osbc_ImpairedLoansMember" name="ImpairedLoansMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="osbc_OtherRealEstateOwnedMember" name="OtherRealEstateOwnedMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="osbc_RealEstateGross" name="RealEstateGross" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="osbc_RealEstatePortfolioSegmentMember" name="RealEstatePortfolioSegmentMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="osbc_OutstandingLoanCommitmentsThresholdForCreditQualityCategorizing" name="OutstandingLoanCommitmentsThresholdForCreditQualityCategorizing" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="debit" />
  <xsd:element id="osbc_RealEstateCostOfRealEstateSoldNetOfGainLoss" name="RealEstateCostOfRealEstateSoldNetOfGainLoss" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="credit" />
  <xsd:element id="osbc_RealEstateAcquiredThroughForeclosureRollForwardTableTextBlock" name="RealEstateAcquiredThroughForeclosureRollForwardTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element id="osbc_AvailableForSaleSecuritiesDebtMaturitiesAmortizedCostWeightedAverageYieldAbstract" name="AvailableForSaleSecuritiesDebtMaturitiesAmortizedCostWeightedAverageYieldAbstract" nillable="true" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element abstract="false" id="osbc_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCostWeightedAverageYield" name="AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCostWeightedAverageYield" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:percentItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="osbc_DiscountedCashFlowValuationTechniqueMember" name="DiscountedCashFlowValuationTechniqueMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="osbc_ScheduleOfContractualCommitmentsDueToLettersOfCreditTableTextBlock" name="ScheduleOfContractualCommitmentsDueToLettersOfCreditTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="osbc_FixedMember" name="FixedMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="osbc_VariableMember" name="VariableMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="osbc_NumberOfCustomersHavingSecuredBalancesExceedingSpecifiedPercentageOfStockholdersEquity" name="NumberOfCustomersHavingSecuredBalancesExceedingSpecifiedPercentageOfStockholdersEquity" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="instant" />
  <xsd:element id="osbc_RealEstateOwnedValuationAllowanceProvisionNetOfAdjustment" name="RealEstateOwnedValuationAllowanceProvisionNetOfAdjustment" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="credit" />
  <xsd:element id="osbc_ScheduleOfAvailableForSaleSecuritiesAndHeldToMaturitySecuritiesReconciliationTableTextBlock" name="ScheduleOfAvailableForSaleSecuritiesAndHeldToMaturitySecuritiesReconciliationTableTextBlock" nillable="true" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" />
  <xsd:element abstract="false" id="osbc_OtherComprehensiveIncomeAvailableForSaleSecuritiesUnrealizedHoldingGainLossNetReclassificationAdjustmentForAmountsRealizedAfterTax" name="OtherComprehensiveIncomeAvailableForSaleSecuritiesUnrealizedHoldingGainLossNetReclassificationAdjustmentForAmountsRealizedAfterTax" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="osbc_FederalHomeLoanBankAdvancesGeneralDebtObligations" name="FederalHomeLoanBankAdvancesGeneralDebtObligations" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="debit" />
  <xsd:element id="osbc_BoardDesignatedCapitalToRiskWeightedAssets" name="BoardDesignatedCapitalToRiskWeightedAssets" nillable="true" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" />
  <xsd:element id="osbc_BoardDesignatedTierOneLeverageCapitalToAverageAssets" name="BoardDesignatedTierOneLeverageCapitalToAverageAssets" nillable="true" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" />
  <xsd:element id="osbc_TimeDeposits100000To250000" name="TimeDeposits100000To250000" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="credit" />
  <xsd:element id="osbc_TimeDeposits250000OrMore" name="TimeDeposits250000OrMore" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="credit" />
  <xsd:element id="osbc_MortgageBackedAndCollateralizedMortgageObligationsMember" name="MortgageBackedAndCollateralizedMortgageObligationsMember" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element id="osbc_CapitalCommonAbstract" name="CapitalCommonAbstract" nillable="true" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element id="osbc_TierOneRiskBasedCapitalCommonEquity" name="TierOneRiskBasedCapitalCommonEquity" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="credit" />
  <xsd:element id="osbc_CommonCapitalToRiskBasedRatiosAbstract" name="CommonCapitalToRiskBasedRatiosAbstract" nillable="true" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element id="osbc_TierOneRiskBasedCapitalCommonEquityToRiskWeightedAssets" name="TierOneRiskBasedCapitalCommonEquityToRiskWeightedAssets" nillable="true" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" />
  <xsd:element id="osbc_TierOneRiskBasedCommonCapitalRequiredForCapitalAdequacy" name="TierOneRiskBasedCommonCapitalRequiredForCapitalAdequacy" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="debit" />
  <xsd:element id="osbc_TierOneRiskBasedCommonCapitalRequiredToBeWellCapitalized" name="TierOneRiskBasedCommonCapitalRequiredToBeWellCapitalized" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="debit" />
  <xsd:element id="osbc_TierOneRiskBasedCommonCapitalRequiredForCapitalAdequacyToRiskWeightedAssets" name="TierOneRiskBasedCommonCapitalRequiredForCapitalAdequacyToRiskWeightedAssets" nillable="true" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" />
  <xsd:element id="osbc_TierOneRiskBasedCommonCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets" name="TierOneRiskBasedCommonCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets" nillable="true" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" />
  <xsd:element id="osbc_TierOneCommonEquityCapitalDistributionLimitationMinimumRegulatoryCapitalPercentageNextTwelveMonths" name="TierOneCommonEquityCapitalDistributionLimitationMinimumRegulatoryCapitalPercentageNextTwelveMonths" nillable="true" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" />
  <xsd:element id="osbc_DividendsDeclaredAndPaidPerShare" name="DividendsDeclaredAndPaidPerShare" nillable="true" type="dtr-types:perShareItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" />
  <xsd:element id="osbc_NetDiscountAccretionOfPurchaseAccountingAdjustmentOnLoans" name="NetDiscountAccretionOfPurchaseAccountingAdjustmentOnLoans" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="credit" />
  <xsd:element id="osbc_MultiFamilyLoanMember" name="MultiFamilyLoanMember" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element id="osbc_GainsLossesOnSalesOfOtherRealEstateBeforeProvisionForValuationAllowance" name="GainsLossesOnSalesOfOtherRealEstateBeforeProvisionForValuationAllowance" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="credit" />
  <xsd:element id="osbc_NumberOfOriginatorsThatCompanyHasInvestedOverSpecifiedPercentageOfItsStockholdersEquity" name="NumberOfOriginatorsThatCompanyHasInvestedOverSpecifiedPercentageOfItsStockholdersEquity" nillable="true" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" />
  <xsd:element id="osbc_DeferredIncomeTaxExpenseBenefitAfterDeferredTaxAssetValuationAdjustment" name="DeferredIncomeTaxExpenseBenefitAfterDeferredTaxAssetValuationAdjustment" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="debit" />
  <xsd:element id="osbc_NetPremiumAmortizationDiscountAccretionOfPurchaseAccountingAdjustmentsOnLoans" name="NetPremiumAmortizationDiscountAccretionOfPurchaseAccountingAdjustmentsOnLoans" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="debit" />
  <xsd:element id="osbc_OsbcAffiliatesMember" name="OsbcAffiliatesMember" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element id="osbc_CommercialLoanCustomersMember" name="CommercialLoanCustomersMember" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element id="osbc_InterestRateLockCommitmentsAndForwardContractsMember" name="InterestRateLockCommitmentsAndForwardContractsMember" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element id="osbc_LeaseRevenueForOtherRealEstate" name="LeaseRevenueForOtherRealEstate" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="credit" />
  <xsd:element id="osbc_MortgageServicingMember" name="MortgageServicingMember" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element id="osbc_ProceedsFromRepaymentsOfOtherShortTermBorrowings" name="ProceedsFromRepaymentsOfOtherShortTermBorrowings" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="debit" />
  <xsd:element id="osbc_FederalDepositInsuranceCorporationPremiumExpenseIncludingAdjustments" name="FederalDepositInsuranceCorporationPremiumExpenseIncludingAdjustments" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="debit" />
  <xsd:element id="osbc_ImpairedFinancingReceivableRelatedAllowanceIncludingPurchasedCreditImpairedLoansAdjustment" name="ImpairedFinancingReceivableRelatedAllowanceIncludingPurchasedCreditImpairedLoansAdjustment" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="credit" />
  <xsd:element id="osbc_EquityIncentivePlan2019Member" name="EquityIncentivePlan2019Member" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element id="osbc_ConditionPerformanceMeasureProRataVestingShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingRightsPercentage" name="ConditionPerformanceMeasureProRataVestingShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingRightsPercentage" nillable="true" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" />
  <xsd:element id="osbc_ConditionPerformanceMeasureFullyEarnedVestingShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingRightsPercentage" name="ConditionPerformanceMeasureFullyEarnedVestingShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingRightsPercentage" nillable="true" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" />
  <xsd:element id="osbc_CommercialRealEstateInvestorMember" name="CommercialRealEstateInvestorMember" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element id="osbc_CommercialRealEstateOwnerOccupiedMember" name="CommercialRealEstateOwnerOccupiedMember" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element id="osbc_RealEstateInvestorMember" name="RealEstateInvestorMember" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element id="osbc_RealEstateOwnerOccupiedMember" name="RealEstateOwnerOccupiedMember" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element id="osbc_ScheduleOfCollateralDependentLoansAndRelatedAllowanceTableTextBlock" name="ScheduleOfCollateralDependentLoansAndRelatedAllowanceTableTextBlock" nillable="true" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" />
  <xsd:element id="osbc_InterestRateLockCommitmentsAndForwardContracts" name="InterestRateLockCommitmentsAndForwardContracts" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="debit" />
  <xsd:element id="osbc_Other2Member" name="Other2Member" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element id="osbc_SubordinatedNotesDue2031Member" name="SubordinatedNotesDue2031Member" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element id="osbc_ThreeMonthsSecuredOvernightFinancingRateMember" name="ThreeMonthsSecuredOvernightFinancingRateMember" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element id="osbc_AllowanceForCreditLossOnUnfundedCommitments" name="AllowanceForCreditLossOnUnfundedCommitments" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="credit" />
  <xsd:element id="osbc_IncreaseDecreaseInAllowanceForCreditLossOnUnfundedCommitments" name="IncreaseDecreaseInAllowanceForCreditLossOnUnfundedCommitments" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="debit" />
  <xsd:element id="osbc_BusinessCombinationEquityInterestIssuedOrIssuableNumberOfSharesForEachShare" name="BusinessCombinationEquityInterestIssuedOrIssuableNumberOfSharesForEachShare" nillable="true" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" />
  <xsd:element id="osbc_BusinessCombinationCashConsiderationPerShare" name="BusinessCombinationCashConsiderationPerShare" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="credit" />
  <xsd:element id="osbc_MinimumPercentageOfSecuritiesInvestmentFromOriginators" name="MinimumPercentageOfSecuritiesInvestmentFromOriginators" nillable="true" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" />
  <xsd:element id="osbc_RealEstateOwnedValuationAllowanceProvisionBenefit" name="RealEstateOwnedValuationAllowanceProvisionBenefit" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="debit" />
  <xsd:element name="NumberOfSecuritiesIssuedFromOriginators" id="osbc_NumberOfSecuritiesIssuedFromOriginators" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" />
  <xsd:element name="OtherShortTermBorrowingsMember" id="osbc_OtherShortTermBorrowingsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="TierOneRiskBasedCapitalRequiredForCapitalAdequacyWithBufferToRiskWeightedAssets" id="osbc_TierOneRiskBasedCapitalRequiredForCapitalAdequacyWithBufferToRiskWeightedAssets" type="xbrli:pureItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" />
  <xsd:element name="TierOneRiskBasedCapitalRequiredForCapitalAdequacyWithBuffer" id="osbc_TierOneRiskBasedCapitalRequiredForCapitalAdequacyWithBuffer" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit" />
  <xsd:element name="MeasurementInputLiquidityPremiumMember" id="osbc_MeasurementInputLiquidityPremiumMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="FinancingReceivableAndNetInvestmentInLeaseNonaccrualNoAllowance" id="osbc_FinancingReceivableAndNetInvestmentInLeaseNonaccrualNoAllowance" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="FinancingReceivableAndNetInvestmentInLeaseRecordedInvestmentNonaccrualStatus" id="osbc_FinancingReceivableAndNetInvestmentInLeaseRecordedInvestmentNonaccrualStatus" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="FinancingReceivableAndNetInvestmentInLeaseBeforeAllowanceForCreditLoss" id="osbc_FinancingReceivableAndNetInvestmentInLeaseBeforeAllowanceForCreditLoss" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="NetTellerAndBillPayingExpense" id="osbc_NetTellerAndBillPayingExpense" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="CashFlowHedgesOfCertainVariableRateCommercialAndCommercialRealEstateLoanPoolsMember" id="osbc_CashFlowHedgesOfCertainVariableRateCommercialAndCommercialRealEstateLoanPoolsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="CashFlowHedgeOfJuniorSubordinatedDebenturesAndWasExecutedToPayFixedAndReceiveVariableRateCashFlowsMember" id="osbc_CashFlowHedgeOfJuniorSubordinatedDebenturesAndWasExecutedToPayFixedAndReceiveVariableRateCashFlowsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="TwoFinancialInstitutionsMember" id="osbc_TwoFinancialInstitutionsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="NumberOfFinancialInstitutionsInWhichCashCollateralPledged" id="osbc_NumberOfFinancialInstitutionsInWhichCashCollateralPledged" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="InvestmentPortfolioEffectiveDuration" id="osbc_InvestmentPortfolioEffectiveDuration" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestAfterAllowanceForCreditLoss" id="osbc_FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestAfterAllowanceForCreditLoss" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="FinancingReceivableAndNetInvestmentInLeaseAllowanceForCreditLossExcludingAccruedInterest" id="osbc_FinancingReceivableAndNetInvestmentInLeaseAllowanceForCreditLossExcludingAccruedInterest" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit" />
  <xsd:element name="FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestBeforeAllowanceForCreditLoss" id="osbc_FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestBeforeAllowanceForCreditLoss" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestCreditLossExpenseReversal" id="osbc_FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestCreditLossExpenseReversal" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestYearOneOriginatedCurrentFiscalYear" id="osbc_FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestYearOneOriginatedCurrentFiscalYear" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeFiscalYear" id="osbc_FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeFiscalYear" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeFiscalYear" id="osbc_FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeFiscalYear" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeFiscalYear" id="osbc_FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeFiscalYear" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeFiscalYear" id="osbc_FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeFiscalYear" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYear" id="osbc_FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYear" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestYearOneOriginatedCurrentFiscalYearWriteoff" id="osbc_FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestYearOneOriginatedCurrentFiscalYearWriteoff" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYearWriteoff" id="osbc_FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYearWriteoff" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYearWriteoff" id="osbc_FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYearWriteoff" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYearWriteoff" id="osbc_FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYearWriteoff" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYearWriteoff" id="osbc_FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYearWriteoff" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYearWriteoff" id="osbc_FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYearWriteoff" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestAllowanceForCreditLossRecovery" id="osbc_FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestAllowanceForCreditLossRecovery" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
  <xsd:element name="FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestAllowanceForCreditLossWriteoff" id="osbc_FinancingReceivableAndNetInvestmentInLeaseExcludingAccruedInterestAllowanceForCreditLossWriteoff" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="FinancingReceivableModifiedTableTextBlock" id="osbc_FinancingReceivableModifiedTableTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="FinancingReceivableModifiedInPeriodToTotalFinancingReceivablesPercentage" id="osbc_FinancingReceivableModifiedInPeriodToTotalFinancingReceivablesPercentage" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="FinancingReceivableModifiedWeightedAveragePaymentDelayFromModification" id="osbc_FinancingReceivableModifiedWeightedAveragePaymentDelayFromModification" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="FinancingReceivableModifiedInPeriodNumberOfContracts" id="osbc_FinancingReceivableModifiedInPeriodNumberOfContracts" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="FinancingReceivableGrossChargeOffsActivityTableTextBlock" id="osbc_FinancingReceivableGrossChargeOffsActivityTableTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="FinancingReceivableAndNetInvestmentInLeaseNonaccrualInterestIncome" id="osbc_FinancingReceivableAndNetInvestmentInLeaseNonaccrualInterestIncome" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
  <xsd:element name="ImpairedFinancingReceivableIncreaseDecreaseOfSpecificAllocationsWithinProvisionForLoanLosses" id="osbc_ImpairedFinancingReceivableIncreaseDecreaseOfSpecificAllocationsWithinProvisionForLoanLosses" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
  <xsd:element name="ScheduleOfFinancingReceivablesAcquiredNotAccountedForAsDebtSecuritiesTableTextBlock" id="osbc_ScheduleOfFinancingReceivablesAcquiredNotAccountedForAsDebtSecuritiesTableTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="ImpairedFinancingReceivableAllowancesForCreditLosses" id="osbc_ImpairedFinancingReceivableAllowancesForCreditLosses" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit" />
  <xsd:element name="FinancingReceivableAndNetInvestmentInLeaseAccruedInterest" id="osbc_FinancingReceivableAndNetInvestmentInLeaseAccruedInterest" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="ScheduleOfUnrealizedLossOnInvestmentsByCategoriesAndLengthOfTimeTableTextBlock" id="osbc_ScheduleOfUnrealizedLossOnInvestmentsByCategoriesAndLengthOfTimeTableTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="ExtendedMaturityAndPaymentModificationMember" id="osbc_ExtendedMaturityAndPaymentModificationMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="InterestRateLockCommitmentsAndForwardContractsLiabilities" id="osbc_InterestRateLockCommitmentsAndForwardContractsLiabilities" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit" />
  <xsd:element name="ExtendedMaturityInterestRateReductionPaymentModificationAndPrincipalReductionMember" id="osbc_ExtendedMaturityInterestRateReductionPaymentModificationAndPrincipalReductionMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="RealEstateOwnedValuationAllowanceAmountsAppliedNetOfAdjustments" id="osbc_RealEstateOwnedValuationAllowanceAmountsAppliedNetOfAdjustments" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="RealEstateAcquisitionsThroughForeclosuresNetOfAcquisitionAdjustmentsAndParticipation" id="osbc_RealEstateAcquisitionsThroughForeclosuresNetOfAcquisitionAdjustmentsAndParticipation" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="BancorpFinancialMember" id="osbc_BancorpFinancialMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="GainsLossesOnSalesOfOtherRealEstateNetOfChangesToValuationAdjustment" id="osbc_GainsLossesOnSalesOfOtherRealEstateNetOfChangesToValuationAdjustment" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
  <xsd:element name="InterestRateCashFlowHedgeLossToBeReclassifiedDuringNext12MonthsNet" id="osbc_InterestRateCashFlowHedgeLossToBeReclassifiedDuringNext12MonthsNet" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="PowersportPortfolioSegmentMember" id="osbc_PowersportPortfolioSegmentMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="InterestExpenseNotesPayableAndLoansPayable" id="osbc_InterestExpenseNotesPayableAndLoansPayable" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsFhlbcStock" id="osbc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsFhlbcStock" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="BusinessCombinationRecognizedAssetAcquiredBankOwnedLifeInsurance" id="osbc_BusinessCombinationRecognizedAssetAcquiredBankOwnedLifeInsurance" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="BusinessCombinationRecognizedLiabilityAssumedNonInterestBearingDemandDeposit" id="osbc_BusinessCombinationRecognizedLiabilityAssumedNonInterestBearingDemandDeposit" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit" />
  <xsd:element name="BusinessCombinationRecognizedLiabilityAssumedInterestBearingDeposit" id="osbc_BusinessCombinationRecognizedLiabilityAssumedInterestBearingDeposit" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit" />
  <xsd:element name="BusinessCombinationRecognizedLiabilityAssumedTotalDeposit" id="osbc_BusinessCombinationRecognizedLiabilityAssumedTotalDeposit" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit" />
  <xsd:element name="BusinessCombinationRecognizedLiabilityAssumedShortTermBorrowings" id="osbc_BusinessCombinationRecognizedLiabilityAssumedShortTermBorrowings" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit" />
  <xsd:element name="BusinessCombinationAcquiredReceivablePurchasedWithCreditDeteriorationGrossContractualAmount" id="osbc_BusinessCombinationAcquiredReceivablePurchasedWithCreditDeteriorationGrossContractualAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="BusinessCombinationAcquiredReceivablePurchasedWithCreditDeteriorationAllowanceForCreditLoss" id="osbc_BusinessCombinationAcquiredReceivablePurchasedWithCreditDeteriorationAllowanceForCreditLoss" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit" />
  <xsd:element name="BusinessCombinationAcquiredReceivablePurchasedWithCreditDeteriorationNonCreditPremium" id="osbc_BusinessCombinationAcquiredReceivablePurchasedWithCreditDeteriorationNonCreditPremium" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="BusinessCombinationAcquiredReceivablePurchasedWithCreditDeteriorationFairValue" id="osbc_BusinessCombinationAcquiredReceivablePurchasedWithCreditDeteriorationFairValue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="NonRiskRatedLoansMember" id="osbc_NonRiskRatedLoansMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="BusinessCombinationAcquisitionRelatedCostsExcludingItem" id="osbc_BusinessCombinationAcquisitionRelatedCostsExcludingItem" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="ConsumerCreditExpense" id="osbc_ConsumerCreditExpense" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="IncreaseDecreaseInOperatingLeaseRightOfUseAsset" id="osbc_IncreaseDecreaseInOperatingLeaseRightOfUseAsset" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
  <xsd:element name="ShareBasedPaymentArrangementTaxBenefitRealizedFromCompensationCost" id="osbc_ShareBasedPaymentArrangementTaxBenefitRealizedFromCompensationCost" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
  <xsd:element name="RealEstateAcquiredThroughForeclosureOperatingIncomeExpenses" id="osbc_RealEstateAcquiredThroughForeclosureOperatingIncomeExpenses" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
  <xsd:element name="RealEstateAcquiredThroughForeclosureGainLossOnTransferToRealEstateOwned" id="osbc_RealEstateAcquiredThroughForeclosureGainLossOnTransferToRealEstateOwned" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
  <xsd:element name="O2026Q3DividendsMember" id="osbc_O2026Q3DividendsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="InterestRateReductionAndPaymentModificationMember" id="osbc_InterestRateReductionAndPaymentModificationMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
</xsd:schema>
