Sodium ethoxide-catalyzed cleavage of azo-N,N′-bis(2, 2-diethoxyethyl)-N,N′-dioxide (2) to an E/Z-mixture (6.5:1) of 1-hydroxyimino-2,2-diethoxyethane (3a) is reported. Alkylation of the oxime sodium salt provides mainly the E-isomers of the alkyloxyimino-2,2-diethoxyethanes 3b-e. The same compounds are also prepared by the reaction of hydroxylamine or O-alkylhydroxylamines with diethoxyacetaldehyde (4). The oxime and the O-alkyloximes were reduced with sodium cyanoborohydride to the corresponding hydroxylamine derivatives 5a-e.