Thermal and photochemical reactions of sodium salts of P-phosphono tosylhydrazones have been investigated. When the sodium salt of dimethyl a-acetylmethylphosphonate tosylhydrazone is heated, the dimethoxyphosphonyl anior , though a relatively strong base, was eliminated. On the other hand, ultraviolet irradiation of the sodium salts of P-phosphono tosylhydrazones leads to dimethoxyphosphonyl-substituted olefins, presumably via the carbene intermediate. Some of the products result from a previously unreported phosphonyl group migration to a carbene.