<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2005-02-22</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001023966</issuerCik>
        <issuerName>ISONICS CORP</issuerName>
        <issuerTradingSymbol>ISON</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001111913</rptOwnerCik>
            <rptOwnerName>ALEXANDER JAMES E</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>ISONICS CORP</rptOwnerStreet1>
            <rptOwnerStreet2>5906 MCINTYRE STREET</rptOwnerStreet2>
            <rptOwnerCity>GOLDEN</rptOwnerCity>
            <rptOwnerState>CO</rptOwnerState>
            <rptOwnerZipCode>80403</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>President</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
                <footnoteId id="F1"/>
                <footnoteId id="F3"/>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>135455</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnotes 1 and 3</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
                <footnoteId id="F2"/>
                <footnoteId id="F3"/>
                <footnoteId id="F8"/>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>500000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnotes 2, 3 and 8</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1185712</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option</value>
                <footnoteId id="F11"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>1.4375</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2004-04-26</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>25000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>1999-04-26</value>
            </exerciseDate>
            <expirationDate>
                <value>2004-04-26</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>25000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Option</value>
                <footnoteId id="F4"/>
                <footnoteId id="F5"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>1.17</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2001-11-13</value>
            </exerciseDate>
            <expirationDate>
                <value>2006-11-13</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>100000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>100000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Option</value>
                <footnoteId id="F4"/>
                <footnoteId id="F6"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>1.25</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2002-03-28</value>
            </exerciseDate>
            <expirationDate>
                <value>2007-03-28</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>20000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>20000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeTransaction>
            <securityTitle>
                <value>Warrant</value>
                <footnoteId id="F4"/>
                <footnoteId id="F7"/>
                <footnoteId id="F12"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>1.25</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2005-02-22</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>50000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2002-03-28</value>
            </exerciseDate>
            <expirationDate>
                <value>2007-03-28</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>150000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>100000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option</value>
                <footnoteId id="F4"/>
                <footnoteId id="F9"/>
                <footnoteId id="F10"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>4.64</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2005-02-22</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>100000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2005-02-22</value>
            </exerciseDate>
            <expirationDate>
                <value>2015-02-22</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>100000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>100000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Shares held by the James and Carol Alexander Foundation, Inc.</footnote>
        <footnote id="F2">Shares Held by spouse.</footnote>
        <footnote id="F3">The reporting person disclaims beneficial ownership of all securities held by his spouse and children and this report should not be deemed an admission that the reporting person is the beneficial owner of such securities for purposes of Section 16 or for any other purpose.</footnote>
        <footnote id="F4">This transaction is exempt by reason of Rule 16b-3(d).</footnote>
        <footnote id="F5">20,000 shares vest on November 13, 2001, and 20,00 shares vest on November 13th of each of the years 2002, 2003, 2004, and 2005.</footnote>
        <footnote id="F6">Options granted by resolution of the Compensation Committee of the Board of Directors as consideration for salary deferral.  The grant of the options is subject to acceptance by the reporting person by no later than April 30, 2002, which acceptance was received.</footnote>
        <footnote id="F7">Warrants to purchase 100,000 shares of common stock vest on March 28, 2002.  The remaining warrants to purchase 50,000 shares of common stock vest and are exercisable only upon the happening of certain events related to a loan made to Isonics Corporation in March 2002.  The grant of the warrants is subject to acceptance by the reporting person by no later than April 30, 2002, which acceptance was received.</footnote>
        <footnote id="F8">This transaction is not a &quot;sale&quot; of securities since it is a gift by the reporting person and is therefore exempt pursuant to Rule 16b-5.  There was no value received for the shares.</footnote>
        <footnote id="F9">Options granted by resolution of the Compensation Committee of the Board of Directors pursuant to the 1996 Executives' Equity Incentive Plan.  The grant of the options is subject to acceptance by the reporting person, which acceptance was received on February 22, 2005.</footnote>
        <footnote id="F10">Such incentive stock options vest at a rate of 20,000 shares immediately on the date of the grant (February 22, 2005) and 20,000 shares on each anniversary of the grant date in each of years 2006, 2007, 2008 and 2009.</footnote>
        <footnote id="F11">These options expired on April 26, 2004.</footnote>
        <footnote id="F12">The 50,000 warrants subject to vesting only upon the happening of certain events did not vest.  This transaction is exempt from Section 16 by reason of Rule 16b-6(b).</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ James E. Alexander</signatureName>
        <signatureDate>2005-02-24</signatureDate>
    </ownerSignature>
</ownershipDocument>
