The hydrolysis of acyl derivatives of malonaldehyde dianil was examined. Alkaline hydrolysis of 1-(N-acetyl-p-methylphenylamino)-3-(p-methylphenylimino)-1-propene (V) in aqueous ethanol gave simply 1-(p-methylphenylamino)-3-(p-methylphenylimino)-1-propene (malonaldehyde dianil of p-toluidine) (VI) and acetic acid. Hydrolysis of 1-(N-benzoyl-p-methylphenylamino)-3-(p-methylphenylimino)-1-propene (VII) in aqueous dioxane in the presence of equimolar amounts of acetic acid and sodium acetate gave β-(p-toluidino) acrolein (VIII), β-(N-benzoyl-p-toluidino) acrolein (XIII) and N-benzoyl-p-toluidine. A small amount of β-(p-toluidino) crotonaldehyde (II) was obtained by hydrolysis of 1-(N-benzoyl-p-methylphenylamino)-3-(p-methylphenylimino)-1-butene (IX). The buffer-catalyzed hydrolysis reaction of VII was followed by measuring the PMR spectrum of the reaction solution to elucidate the sequence of the reaction process.