<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0101</schemaVersion>

    <documentType>4</documentType>
    <periodOfReport>2003-07-16</periodOfReport>
    <notSubjectToSection16>0</notSubjectToSection16>
    <issuer>
        <issuerCik>0001067092</issuerCik>
        <issuerName>BANK ONE CORP</issuerName>
        <issuerTradingSymbol>ONE</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001185064</rptOwnerCik>
            <rptOwnerName>CROWN JAMES S</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>  </rptOwnerStreet1>
            <rptOwnerStreet2>  </rptOwnerStreet2>
            <rptOwnerCity>  </rptOwnerCity>
            <rptOwnerState>  </rptOwnerState>
            <rptOwnerZipCode>  </rptOwnerZipCode>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>
   <derivativeSecurity>
      <securityTitle>
          <value>Stock Units</value>
      </securityTitle>
      <conversionOrExercisePrice>
          <value>1.00</value>
      </conversionOrExercisePrice>
      <transactionDate>
          <value>2003-07-16</value>
      </transactionDate>
      <transactionCoding>
          <transactionFormType>4</transactionFormType>
          <transactionCode>A</transactionCode>
          <equitySwapInvolved>0</equitySwapInvolved>
              <footnoteId id="F1" />
      </transactionCoding>
      <transactionAmounts>
          <transactionShares>
              <value>288.00</value>
          </transactionShares>
          <transactionValue>
              <value>0</value>
          </transactionValue>
          <transactionAcquiredDisposedCode>
              <value>A</value>
          </transactionAcquiredDisposedCode>
      </transactionAmounts>
      <exerciseDate>
          <value>1988-08-08</value>
              <footnoteId id="F1" />
      </exerciseDate>
      <expirationDate>
          <value>1988-08-08</value>
              <footnoteId id="F1" />
      </expirationDate>
      <underlyingSecurity>
          <underlyingSecurityTitle>
              <value>Common Stock</value>
          </underlyingSecurityTitle>
          <underlyingSecurityShares>
              <value>288.00</value>
          </underlyingSecurityShares>
      </underlyingSecurity>
      <postTransactionAmounts>
          <sharesOwnedFollowingTransaction>
              <value>32238.00</value>
          </sharesOwnedFollowingTransaction>
      </postTransactionAmounts>
      <ownershipNature>
          <directOrIndirectOwnership>
              <value>D</value>
          </directOrIndirectOwnership>
      </ownershipNature>
   </derivativeSecurity>
<footnotes>
   <footnote id="F1">Stock units granted under the Corporation's Director Stock Plan.  Each unit represents the right to receive a share of the Corporation's common stock after Reporting Person's retirement, on a 1 for 1 basis, and dividend equivalent rights which will be reinvested in additional stock units.</footnote>
</footnotes>
    <ownerSignature>
       <signatureName>James S. Crown</signatureName>
       <signatureDate>2003-07-17</signatureDate>
    </ownerSignature>
    <ownerSignature>
       <signatureName>/s/ Laurence Goldman, Attorney</signatureName>
       <signatureDate>2003-07-17</signatureDate>
    </ownerSignature>
</ownershipDocument>

