Abstract: A novel and efficient method has been developed for the synthesis of N, N- dialkylamino-O-alkyl-2-(1-methyl-2-oxopropylidene) phosphorohydrazido oximes 5. The reactions involve the condensation of diacetylmonoxime and N, N-dialkylamino-O- alkylphosphorohydrazides in the presence of activated silica and give the corresponding target oximes in excellent yields under mild conditions.