<?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>0001360177</rptOwnerCik>
            <rptOwnerName>DENG TIANZHOU</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1603-1604,TOWER B FORTUNE CENTRE AO CITY</rptOwnerStreet1>
            <rptOwnerStreet2>BEIYUAN ROAD, CHAOYANG DISTRICT</rptOwnerStreet2>
            <rptOwnerCity>BEIJING</rptOwnerCity>
            <rptOwnerState>F4</rptOwnerState>
            <rptOwnerZipCode>0</rptOwnerZipCode>
            <rptOwnerStateDescription>CHINA</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</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>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Skywide Capital Management Limited</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Options (Right to buy)</value>
                <footnoteId id="F3"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>2</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2010-09-27</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F3"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>100000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2007-04-09</value>
            </exerciseDate>
            <expirationDate>
                <value>2012-04-09</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>100000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </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 beneficially owned by Mr. Deng 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>
        <footnote id="F2">Mr. Deng owns 50% of the stock of Skywide.  The number of shares beneficially owned by Mr. Deng represents 50% of the shares owned by Skywide.</footnote>
        <footnote id="F3">On September 27, 2010, the transactions contemplated by the Agreement were consummated. Upon closing, all of the stock options of the Issuer which were beneficially owned by Mr. Deng were cancelled</footnote>
    </footnotes>

    <remarks></remarks>

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