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

    <schemaVersion>X0603</schemaVersion>

    <submissionType>D/A</submissionType>

    <testOrLive>LIVE</testOrLive>

    <primaryIssuer>
        <cik>0001456359</cik>
        <entityName>ENERGY CAPITAL PARTNERS II-B, LP</entityName>
        <issuerAddress>
            <street1>51 JOHN F. KENNEDY PARKWAY</street1>
            <street2>SUITE 200</street2>
            <city>SHORT HILLS</city>
            <stateOrCountry>NJ</stateOrCountry>
            <zipCode>07078</zipCode>
        </issuerAddress>
        <issuerPhoneNumber>973-671-6100</issuerPhoneNumber>
        <jurisdictionOfInc>DELAWARE</jurisdictionOfInc>
        <edgarPreviousNameList>
            <previousName>ENERGY CAPITAL PARTNERS II B LP</previousName>
        </edgarPreviousNameList>
        <entityType>Limited Partnership</entityType>
        <yearOfInc>
            <withinFiveYears>true</withinFiveYears>
            <value>2008</value>
        </yearOfInc>
    </primaryIssuer>

    <relatedPersonsList>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>DOUGLAS</firstName>
                <middleName>W.</middleName>
                <lastName>KIMMELMAN</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>51 JOHN F. KENNEDY PARKWAY</street1>
                <street2>SUITE 200</street2>
                <city>SHORT HILLS</city>
                <stateOrCountry>NJ</stateOrCountry>
                <zipCode>07078</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Executive Officer</relationship>
                <relationship>Promoter</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>SCOTT</firstName>
                <middleName>B.</middleName>
                <lastName>HELM</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>51 JOHN F. KENNEDY PARKWAY</street1>
                <street2>SUITE 200</street2>
                <city>SHORT HILLS</city>
                <stateOrCountry>NJ</stateOrCountry>
                <zipCode>07078</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Executive Officer</relationship>
                <relationship>Promoter</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>PETER</firstName>
                <lastName>LABBAT</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>51 JOHN F. KENNEDY PARKWAY</street1>
                <street2>SUITE 200</street2>
                <city>SHORT HILLS</city>
                <stateOrCountry>NJ</stateOrCountry>
                <zipCode>07078</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Executive Officer</relationship>
                <relationship>Promoter</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>THOMAS</firstName>
                <middleName>K.</middleName>
                <lastName>LANE</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>51 JOHN F. KENNEDY PARKWAY</street1>
                <street2>SUITE 200</street2>
                <city>SHORT HILLS</city>
                <stateOrCountry>NJ</stateOrCountry>
                <zipCode>07078</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Executive Officer</relationship>
                <relationship>Promoter</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>ANDREW</firstName>
                <middleName>D.</middleName>
                <lastName>SINGER</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>11943 EL CAMINO REAL</street1>
                <street2>SUITE 220</street2>
                <city>SAN DIEGO</city>
                <stateOrCountry>CA</stateOrCountry>
                <zipCode>92130</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Executive Officer</relationship>
                <relationship>Promoter</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>PERRY</firstName>
                <middleName>J.</middleName>
                <lastName>COLE</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>11943 EL CAMINO REAL</street1>
                <street2>SUITE 220</street2>
                <city>SAN DIEGO</city>
                <stateOrCountry>CA</stateOrCountry>
                <zipCode>92130</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Executive Officer</relationship>
                <relationship>Promoter</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>STEVEN</firstName>
                <middleName>A.</middleName>
                <lastName>HERMAN</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>51 JOHN F. KENNEDY PARKWAY</street1>
                <street2>SUITE 200</street2>
                <city>SHORT HILLS</city>
                <stateOrCountry>NJ</stateOrCountry>
                <zipCode>07078</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Executive Officer</relationship>
                <relationship>Promoter</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>MURRAY</firstName>
                <middleName>D.</middleName>
                <lastName>KARP</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>51 JOHN F. KENNEDY PARKWAY</street1>
                <street2>SUITE 200</street2>
                <city>SHORT HILLS</city>
                <stateOrCountry>NJ</stateOrCountry>
                <zipCode>07078</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Executive Officer</relationship>
                <relationship>Promoter</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>PAUL</firstName>
                <middleName>C.</middleName>
                <lastName>PARSHLEY</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>51 JOHN F. KENNEDY PARKWAY</street1>
                <street2>SUITE 200</street2>
                <city>SHORT HILLS</city>
                <stateOrCountry>NJ</stateOrCountry>
                <zipCode>07078</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Executive Officer</relationship>
                <relationship>Promoter</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
    </relatedPersonsList>

    <offeringData>
        <industryGroup>
            <industryGroupType>Pooled Investment Fund</industryGroupType>
            <investmentFundInfo>
                <investmentFundType>Private Equity Fund</investmentFundType>
                <is40Act>false</is40Act>
            </investmentFundInfo>
        </industryGroup>
        <issuerSize>
            <revenueRange>Decline to Disclose</revenueRange>
        </issuerSize>
        <federalExemptionsExclusions>
            <item>06</item>
            <item>3C</item>
            <item>3C.7</item>
        </federalExemptionsExclusions>
        <typeOfFiling>
            <newOrAmendment>
                <isAmendment>true</isAmendment>
                <previousAccessionNumber>9999999997-09-004017</previousAccessionNumber>
            </newOrAmendment>
            <dateOfFirstSale>
                <value>2009-06-25</value>
            </dateOfFirstSale>
        </typeOfFiling>
        <durationOfOffering>
            <moreThanOneYear>true</moreThanOneYear>
        </durationOfOffering>
        <typesOfSecuritiesOffered>
            <isEquityType>true</isEquityType>
            <isPooledInvestmentFundType>true</isPooledInvestmentFundType>
        </typesOfSecuritiesOffered>
        <businessCombinationTransaction>
            <isBusinessCombinationTransaction>false</isBusinessCombinationTransaction>
            <clarificationOfResponse></clarificationOfResponse>
        </businessCombinationTransaction>
        <minimumInvestmentAccepted>0</minimumInvestmentAccepted>
        <salesCompensationList>
            <recipient>
                <recipientName>PARK HILL GROUP LLC</recipientName>
                <recipientCRDNumber>135898</recipientCRDNumber>
                <associatedBDName>None</associatedBDName>
                <associatedBDCRDNumber>None</associatedBDCRDNumber>
                <recipientAddress>
                    <street1>345 PARK AVENUE, 15TH FLOOR</street1>
                    <city>NEW YORK</city>
                    <stateOrCountry>NY</stateOrCountry>
                    <zipCode>10154</zipCode>
                </recipientAddress>
                <statesOfSolicitationList>
                    <value>All States</value>
                </statesOfSolicitationList>
            </recipient>
            <recipient>
                <recipientName>BEL AIR SECURITIES LLC</recipientName>
                <recipientCRDNumber>134953</recipientCRDNumber>
                <associatedBDName>None</associatedBDName>
                <associatedBDCRDNumber>None</associatedBDCRDNumber>
                <recipientAddress>
                    <street1>1999 AVENUE OF THE STARS, SUITE 2800</street1>
                    <city>LOS ANGELES</city>
                    <stateOrCountry>CA</stateOrCountry>
                    <zipCode>90067</zipCode>
                </recipientAddress>
                <statesOfSolicitationList>
                    <state>CA</state>
                    <state>CO</state>
                    <state>DE</state>
                    <state>IL</state>
                    <state>MN</state>
                    <state>NV</state>
                    <state>NY</state>
                </statesOfSolicitationList>
            </recipient>
        </salesCompensationList>
        <offeringSalesAmounts>
            <totalOfferingAmount>1874650000</totalOfferingAmount>
            <totalAmountSold>134900000</totalAmountSold>
            <totalRemaining>1739750000</totalRemaining>
            <clarificationOfResponse>Energy Capital Partners GP II, LP (the &quot;General Partner&quot; of the Issuer), reserves the right to offer a greater or lesser amount of limited partner interests.</clarificationOfResponse>
        </offeringSalesAmounts>
        <investors>
            <hasNonAccreditedInvestors>false</hasNonAccreditedInvestors>
            <totalNumberAlreadyInvested>24</totalNumberAlreadyInvested>
        </investors>
        <salesCommissionsFindersFees>
            <salesCommissions>
                <dollarAmount>8000000</dollarAmount>
                <isEstimate>true</isEstimate>
            </salesCommissions>
            <findersFees>
                <dollarAmount>0</dollarAmount>
                <isEstimate>true</isEstimate>
            </findersFees>
            <clarificationOfResponse>Estimated sales commissions are for the Issuer and its parallel funds.</clarificationOfResponse>
        </salesCommissionsFindersFees>
        <useOfProceeds>
            <grossProceedsUsed>
                <dollarAmount>360000000</dollarAmount>
                <isEstimate>true</isEstimate>
            </grossProceedsUsed>
            <clarificationOfResponse>Estimated aggregate amount of management fees for the Issuer and its parallel funds for the first six years.  The Issuer and its parallel funds will continue to pay management fees thereafter.</clarificationOfResponse>
        </useOfProceeds>
        <signatureBlock>
            <authorizedRepresentative>false</authorizedRepresentative>
            <signature>
                <issuerName>ENERGY CAPITAL PARTNERS II-B, LP</issuerName>
                <signatureName>/s/ Andrew D. Singer</signatureName>
                <nameOfSigner>Andrew D. Singer</nameOfSigner>
                <signatureTitle>Managing Member of the GP of the GP of the Issuer</signatureTitle>
                <signatureDate>2010-02-10</signatureDate>
            </signature>
        </signatureBlock>
    </offeringData>
</edgarSubmission>
