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

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2010-09-27</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0001107563</issuerCik>
        <issuerName>Sinoenergy CORP</issuerName>
        <issuerTradingSymbol>SNEN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001360078</rptOwnerCik>
            <rptOwnerName>SKYWIDE CAPITAL MANAGEMENT LTD</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>P.O BOX 3444</rptOwnerStreet1>
            <rptOwnerStreet2>ROAD TOWN</rptOwnerStreet2>
            <rptOwnerCity>TORTOLA</rptOwnerCity>
            <rptOwnerState>D8</rptOwnerState>
            <rptOwnerZipCode>0</rptOwnerZipCode>
            <rptOwnerStateDescription>VIRGIN ISLANDS, BRITISH</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2010-09-27</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>0</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">On September 27, 2010, the transactions contemplated by the Amended and Restated Agreement and Plan of Merger, dated as of March 29, 2010 (the &quot;Agreement&quot;), by and among Skywide Capital Management Limited, a company incorporated with limited liability under the laws of the British Virgin Islands(&quot;Skywide&quot;), SNEN Acquisition Corp., a corporation organized under the laws of the state of Nevada and a wholly-owned subsidiary of the Buyer (the &quot;Buyer Subsidiary&quot;) and the Issuer were consummated.
Upon closing, all of the shares of the Issuer which were owned by Skywide were cancelled, and each of the 1,000 shares of common stock of the Buyer Subsidiary owned by Skywide as of the closing date were converted into shares of the Issuer.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Tianzhou Deng</signatureName>
        <signatureDate>2010-09-29</signatureDate>
    </ownerSignature>
</ownershipDocument>
