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

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2010-09-24</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000856569</issuerCik>
        <issuerName>ENCORIUM GROUP INC</issuerName>
        <issuerTradingSymbol>enco</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001497733</rptOwnerCik>
            <rptOwnerName>Dieter-Albrecht Klaus</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>ENCORIUM OY</rptOwnerStreet1>
            <rptOwnerStreet2>KEILARANTA 10</rptOwnerStreet2>
            <rptOwnerCity>ESPOO</rptOwnerCity>
            <rptOwnerState>H9</rptOwnerState>
            <rptOwnerZipCode>FI-02150</rptOwnerZipCode>
            <rptOwnerStateDescription>FINLAND</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Vice President</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2010-09-24</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>58140</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>2.5</value>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>58140</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Issued as part of the consideration paid for the Company's acquisition of Progenitor Holding AG pursuant to the Stock Purchase Agreement between the Company and the shareholders of Progenitor Holding AG dated July 19, 2010.  Pursuant to the Stock Purchase Agreement each share was valued at $2.50.</footnote>
        <footnote id="F2">See Footnote 1.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Klaus-Dieter Albrecht</signatureName>
        <signatureDate>2010-09-24</signatureDate>
    </ownerSignature>
</ownershipDocument>
