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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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 SjgqzFAi8EW7lqlXZRV46w==

<SEC-DOCUMENT>0001104659-08-078290.txt : 20081223
<SEC-HEADER>0001104659-08-078290.hdr.sgml : 20081223
<ACCEPTANCE-DATETIME>20081223185343
ACCESSION NUMBER:		0001104659-08-078290
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20081220
FILED AS OF DATE:		20081223
DATE AS OF CHANGE:		20081223

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			PLUG POWER INC
		CENTRAL INDEX KEY:			0001093691
		STANDARD INDUSTRIAL CLASSIFICATION:	ELECTRICAL INDUSTRIAL APPARATUS [3620]
		IRS NUMBER:				223672377
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		968 ALBANY-SHAKER ROAD
		CITY:			LATHAM
		STATE:			NY
		ZIP:			12110
		BUSINESS PHONE:		5187827700

	MAIL ADDRESS:	
		STREET 1:		968 ALBANY-SHAKER ROAD
		CITY:			LATHAM
		STATE:			NY
		ZIP:			12110

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			SMART HYDROGEN, INC.
		CENTRAL INDEX KEY:			0001359862
		STATE OF INCORPORATION:			D8
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-27527
		FILM NUMBER:		081268607

	BUSINESS ADDRESS:	
		STREET 1:		135 ARCH. MAKARIOS III AVE
		STREET 2:		EMELLE BLDG 2ND FLOOR, OFFICE NO. 22
		CITY:			LIMASSOL
		STATE:			G4
		ZIP:			CY-3021
		BUSINESS PHONE:		357-2587-0762

	MAIL ADDRESS:	
		STREET 1:		135 ARCH. MAKARIOS III AVE
		STREET 2:		EMELLE BLDG 2ND FLOOR, OFFICE NO. 22
		CITY:			LIMASSOL
		STATE:			G4
		ZIP:			CY-3021

	FORMER NAME:	
		FORMER CONFORMED NAME:	Smart Hydrogen Inc
		DATE OF NAME CHANGE:	20060419

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Clayburn Development Inc.
		CENTRAL INDEX KEY:			0001359865
		STATE OF INCORPORATION:			D8
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-27527
		FILM NUMBER:		081268606

	BUSINESS ADDRESS:	
		STREET 1:		PASEA ESTATE
		STREET 2:		ROAD TOWN
		CITY:			TORTOLA
		STATE:			D8
		ZIP:			00000
		BUSINESS PHONE:		357 25 87 07 62

	MAIL ADDRESS:	
		STREET 1:		PASEA ESTATE
		STREET 2:		ROAD TOWN
		CITY:			TORTOLA
		STATE:			D8
		ZIP:			00000

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Branton LTD
		CENTRAL INDEX KEY:			0001359849
		STATE OF INCORPORATION:			C5
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-27527
		FILM NUMBER:		081268605

	BUSINESS ADDRESS:	
		STREET 1:		KING COURT, 1ST FLOOR, BAY STREET
		STREET 2:		P.O. BOX N-3944
		CITY:			NASSAU
		STATE:			C5
		ZIP:			00000
		BUSINESS PHONE:		357 25 868 000

	MAIL ADDRESS:	
		STREET 1:		KING COURT, 1ST FLOOR, BAY STREET
		STREET 2:		P.O. BOX N-3944
		CITY:			NASSAU
		STATE:			C5
		ZIP:			00000
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>a4.xml
<DESCRIPTION>4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-12-20</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0001093691</issuerCik>
        <issuerName>PLUG POWER INC</issuerName>
        <issuerTradingSymbol>PLUG</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001359862</rptOwnerCik>
            <rptOwnerName>SMART HYDROGEN, INC.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>135 ARCH. MAKARIOS III AVE</rptOwnerStreet1>
            <rptOwnerStreet2>EMELLE BLDG 2ND FLOOR, OFFICE NO. 22</rptOwnerStreet2>
            <rptOwnerCity>LIMASSOL</rptOwnerCity>
            <rptOwnerState>G4</rptOwnerState>
            <rptOwnerZipCode>CY-3021</rptOwnerZipCode>
            <rptOwnerStateDescription>CYPRUS</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001359865</rptOwnerCik>
            <rptOwnerName>Clayburn Development Inc.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>PASEA ESTATE</rptOwnerStreet1>
            <rptOwnerStreet2>ROAD TOWN</rptOwnerStreet2>
            <rptOwnerCity>TORTOLA</rptOwnerCity>
            <rptOwnerState>D8</rptOwnerState>
            <rptOwnerZipCode>00000</rptOwnerZipCode>
            <rptOwnerStateDescription>VIRGIN ISLANDS, BRITISH</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001359849</rptOwnerCik>
            <rptOwnerName>Branton LTD</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>KING COURT, 1ST FLOOR, BAY STREET</rptOwnerStreet1>
            <rptOwnerStreet2>P.O. BOX N-3944</rptOwnerStreet2>
            <rptOwnerCity>NASSAU</rptOwnerCity>
            <rptOwnerState>C5</rptOwnerState>
            <rptOwnerZipCode>00000</rptOwnerZipCode>
            <rptOwnerStateDescription>BAHAMAS</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, par value $0.01</value>
            </securityTitle>
            <transactionDate>
                <value>2008-12-20</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>5126939</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.74</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F1"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Class B Capital Stock, par value $0.01</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F2"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2008-12-20</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>395000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.74</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock, par value $0.01</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>39500000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F1"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The shares reported above were held directly by Smart Hydrogen Inc. (&quot;Smart Hydrogen&quot;), which is jointly owned and controlled by Clayburn Development Inc. (&quot;Clayburn&quot;) and Branton Limited (&quot;Branton&quot;). Branton and Clayburn share investment control and controlling shareholder status over Smart Hydrogen and, as such, were indirect beneficial owners of the reported shares of Common Stock and Class B Capital Stock. Clayburn is a wholly-owned subsidiary of MMC Norilsk Nickel.</footnote>
        <footnote id="F2">Upon the disposition of the Class B Capital Stock reported in this Form 4, each share of Class B Capital Stock automatically converted into 100 Shares of Plug Power Inc.'s Common Stock, par value $0.01 per share.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Athina Karelidou, Director of Smart Hydrogen Inc.</signatureName>
        <signatureDate>2008-12-23</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Andrey Smirnov, Attorney-In-Fact for Clayburn Development Inc.</signatureName>
        <signatureDate>2008-12-23</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Maria Lambrianidou, Director of Branton Limited</signatureName>
        <signatureDate>2008-12-23</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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