Phosphoramides are prepared for enzyme studies.These compounds can be easily obtained by refluxing one mole of amidodichlorophosphate and two moles of anhydrous formic acid in an anhydrous organic solvent for about three hours.The high yield and the simple procedure for isolation of the product make this method superior to those described in the literature.By this method we have so far obtained the phosphoramide compounds of aniline, p-chloroaniline, a-naphthylamine, sulfanilamide, o-methoxyaniline.p-toluidine and benzylamine.However, this method has failed in the preparation of N-(p-nitrophenyl) amidophosphoric acid and N-(p-carboxyphenyl) amidophosphoric acid.The latter can be obtained by the reaction of amidophosphoryldichloride of p-aminobenzoyl chloride and formic acid.