<?xml version="1.0"?>
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    <schemaVersion>X0704</schemaVersion>

    <submissionType>D</submissionType>

    <testOrLive>LIVE</testOrLive>

    <primaryIssuer>
        <cik>0001366388</cik>
        <entityName>SIONYX INC</entityName>
        <issuerAddress>
            <street1>100 CUMMINGS CENTER</street1>
            <city>BEVERLY</city>
            <stateOrCountry>MA</stateOrCountry>
            <stateOrCountryDescription>MASSACHUSETTS</stateOrCountryDescription>
            <zipCode>01915</zipCode>
        </issuerAddress>
        <issuerPhoneNumber>978-922-0684</issuerPhoneNumber>
        <jurisdictionOfInc>DELAWARE</jurisdictionOfInc>
        <issuerPreviousNameList>
            <value>None</value>
        </issuerPreviousNameList>
        <edgarPreviousNameList>
            <value>None</value>
        </edgarPreviousNameList>
        <entityType>Corporation</entityType>
        <yearOfInc>
            <overFiveYears>true</overFiveYears>
        </yearOfInc>
    </primaryIssuer>

    <relatedPersonsList>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Stephen</firstName>
                <middleName>D.</middleName>
                <lastName>Saylor</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>c/o SiOnyx, Inc.</street1>
                <street2>100 Cummings Center, Suite 244G</street2>
                <city>Beverly</city>
                <stateOrCountry>MA</stateOrCountry>
                <stateOrCountryDescription>MASSACHUSETTS</stateOrCountryDescription>
                <zipCode>01915</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Executive Officer</relationship>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>James</firstName>
                <middleName>E.</middleName>
                <lastName>Carey, III</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>c/o SiOnyx, Inc.</street1>
                <street2>100 Cummings Center, Suite 244G</street2>
                <city>Beverly</city>
                <stateOrCountry>MA</stateOrCountry>
                <stateOrCountryDescription>MASSACHUSETTS</stateOrCountryDescription>
                <zipCode>01915</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Executive Officer</relationship>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Daniel</firstName>
                <middleName>B.</middleName>
                <lastName>Wolfe</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>c/o Harris &amp; Harris Group, Inc.</street1>
                <street2>1450 West Broadway, 24th Floor</street2>
                <city>New York</city>
                <stateOrCountry>NY</stateOrCountry>
                <stateOrCountryDescription>NEW YORK</stateOrCountryDescription>
                <zipCode>10019</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Richard</firstName>
                <middleName>L.</middleName>
                <lastName>Harris</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>c/o RedShift Ventures</street1>
                <street2>3057 Nutley Street, Suite 562</street2>
                <city>Fairfax</city>
                <stateOrCountry>VA</stateOrCountry>
                <stateOrCountryDescription>VIRGINIA</stateOrCountryDescription>
                <zipCode>22031</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
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            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Robert</firstName>
                <lastName>Metcalfe</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>c/o Polaris Venture Partners</street1>
                <street2>1000 Winter Street, Suite 3350</street2>
                <city>Waltham</city>
                <stateOrCountry>MA</stateOrCountry>
                <stateOrCountryDescription>MASSACHUSETTS</stateOrCountryDescription>
                <zipCode>02451</zipCode>
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            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
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            <relationshipClarification></relationshipClarification>
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        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Michael</firstName>
                <lastName>Hawley</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>101 Third Street, Unit 3</street1>
                <city>Cambridge</city>
                <stateOrCountry>MA</stateOrCountry>
                <stateOrCountryDescription>MASSACHUSETTS</stateOrCountryDescription>
                <zipCode>02141</zipCode>
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            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
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            <relationshipClarification></relationshipClarification>
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        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Jeannine</firstName>
                <lastName>Sargent</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>2270 Kendle Street</street1>
                <city>Cuppertino</city>
                <stateOrCountry>CA</stateOrCountry>
                <stateOrCountryDescription>CALIFORNIA</stateOrCountryDescription>
                <zipCode>95014</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
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            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Paul</firstName>
                <lastName>Russo</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>13050 La Paloma Road</street1>
                <city>Los Altos Hills</city>
                <stateOrCountry>CA</stateOrCountry>
                <stateOrCountryDescription>CALIFORNIA</stateOrCountryDescription>
                <zipCode>94022</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
    </relatedPersonsList>

    <offeringData>
        <industryGroup>
            <industryGroupType>Other Technology</industryGroupType>
        </industryGroup>
        <issuerSize>
            <revenueRange>Decline to Disclose</revenueRange>
        </issuerSize>
        <federalExemptionsExclusions>
            <item>06</item>
        </federalExemptionsExclusions>
        <typeOfFiling>
            <newOrAmendment>
                <isAmendment>false</isAmendment>
            </newOrAmendment>
            <dateOfFirstSale>
                <value>2010-06-08</value>
            </dateOfFirstSale>
        </typeOfFiling>
        <durationOfOffering>
            <moreThanOneYear>false</moreThanOneYear>
        </durationOfOffering>
        <typesOfSecuritiesOffered>
            <isEquityType>true</isEquityType>
        </typesOfSecuritiesOffered>
        <businessCombinationTransaction>
            <isBusinessCombinationTransaction>false</isBusinessCombinationTransaction>
            <clarificationOfResponse></clarificationOfResponse>
        </businessCombinationTransaction>
        <minimumInvestmentAccepted>0</minimumInvestmentAccepted>
        <salesCompensationList></salesCompensationList>
        <offeringSalesAmounts>
            <totalOfferingAmount>12000000</totalOfferingAmount>
            <totalAmountSold>6300000</totalAmountSold>
            <totalRemaining>5700000</totalRemaining>
            <clarificationOfResponse></clarificationOfResponse>
        </offeringSalesAmounts>
        <investors>
            <hasNonAccreditedInvestors>false</hasNonAccreditedInvestors>
            <totalNumberAlreadyInvested>0</totalNumberAlreadyInvested>
        </investors>
        <salesCommissionsFindersFees>
            <salesCommissions>
                <dollarAmount>0</dollarAmount>
            </salesCommissions>
            <findersFees>
                <dollarAmount>0</dollarAmount>
            </findersFees>
            <clarificationOfResponse></clarificationOfResponse>
        </salesCommissionsFindersFees>
        <useOfProceeds>
            <grossProceedsUsed>
                <dollarAmount>0</dollarAmount>
                <isEstimate>true</isEstimate>
            </grossProceedsUsed>
            <clarificationOfResponse></clarificationOfResponse>
        </useOfProceeds>
        <signatureBlock>
            <authorizedRepresentative>false</authorizedRepresentative>
            <signature>
                <issuerName>SIONYX INC</issuerName>
                <signatureName>Stephen D. Saylor</signatureName>
                <nameOfSigner>Stephen D. Saylor</nameOfSigner>
                <signatureTitle>President and CEO</signatureTitle>
                <signatureDate>2010-06-22</signatureDate>
            </signature>
        </signatureBlock>
    </offeringData>
</edgarSubmission>
