The anodic oxidation of sulfamate, products of which are known to significantly affect the quality of nickel deposits in a nickel electroforming bath, has been studied. Sulfamate was oxidized electrochemically at a platinum electrode in aqueous solution of initial pH 12 and 2, and one of the decomposition products produced therefrom, which had not been identified in the literature, was separated by means of paper chromatographic methods and subjected to spectroscopic analysis. The compound is produced at an applied potential more positive than 1.2 and 1.8 V vs Ag/AgCl, saturated KCl electrode in alkaline and acidic media, respectively. The analysis indicates that the compound has spectroscopic and chromatographic characteristics consistent with a new, thus far unknown compound, diimide S-sulfonate, H2N=N-S-SO3 which may have two different tautomeric structures. An oxidation mechanism for sulfamate consistent with the generation of this product is proposed.