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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2015-09-14</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001162816</issuerCik>
        <issuerName>NEAH POWER SYSTEMS, INC.</issuerName>
        <issuerTradingSymbol>NPWZ</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001412303</rptOwnerCik>
            <rptOwnerName>D'COUTO GERARD C</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>22118 20TH AVENUE SE</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 142</rptOwnerStreet2>
            <rptOwnerCity>BOTHELL</rptOwnerCity>
            <rptOwnerState>WA</rptOwnerState>
            <rptOwnerZipCode>98021</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CEO and President</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Warrant To Purchase Common Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.0031</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2015-09-14</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>187341935</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2016-03-14</value>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2020-09-13</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>187341935</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>331014828</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Exercisable upon the earlier of six (6) month anniversary of issue date or the date an amendment is filed with the Secretary of Nevada increasing the authorized shares of the Company common stock.</footnote>
        <footnote id="F2">No readily determinable value.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Gerard C D'Couto</signatureName>
        <signatureDate>2015-09-14</signatureDate>
    </ownerSignature>
</ownershipDocument>
