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

    <schemaVersion>X0304</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2012-03-08</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000047307</issuerCik>
        <issuerName>HICKOK INC</issuerName>
        <issuerTradingSymbol>HICKA</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001243286</rptOwnerCik>
            <rptOwnerName>SLADE JANET H</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O HICKOK INCORPORATED</rptOwnerStreet1>
            <rptOwnerStreet2>10514 DUPONT AVE</rptOwnerStreet2>
            <rptOwnerCity>CLEVELAND</rptOwnerCity>
            <rptOwnerState>OH</rptOwnerState>
            <rptOwnerZipCode>44108</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>2.925</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2012-03-08</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2022-03-08</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common Shares</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>10000</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Granted pursuant to the Hickok Incorporated 2010 Outside Directors Stock Option Plan which complies with Rule 16b-3. These options become exercisable in equal 33% increments over three years beginning on the first anniversary of the date of the grant.</footnote>
        <footnote id="F2">The reporting person still holds previously reported options to buy 9,000 Class A Common Shares granted pursuant to the Hickok Incorporated 2000 Outside Directors Stock Option Plan, the Hickok Incorporated 2003 Outside Directors Stock Option Plan, the Hickok Incorporated 2007 Outside Directors Stock Option Plan and the Hickok Incorporated 2010 Outside Directors Stock Option Plan. All these plans comply with Rule 16b-3. These options were granted between February 21, 2003 and February 24, 2011 at exercise prices ranging from $2.925 to $11.00, become or became exercisable between February 21, 2004 and February 24, 2014, and will expire between February 21, 2013 and February 24, 2021. The total number of options set forth in column No. 9 reflects the expiration of options to purchase 1,000 Class A Common Shares granted to the reporting person on February 21, 2002, which options expired on February 21, 2012.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Janet H. Slade</signatureName>
        <signatureDate>2012-03-13</signatureDate>
    </ownerSignature>
</ownershipDocument>
