A new convenient method for the synthesis of earlier unknown 2 substituted derivatives of 5 phenylaminomethyl 2,4 dihydro 3H [1,2,4]triazol 3 ones was developed. The method in volved the alkaline hydrolysis of 2 alkyl 6 phenyl 6,7 dihydro 3H imidazo[5,1 c] [1,2,4] triazole 3,5(2H) diones obtained by alkylation of 6 phenyl 6,7 dihydro 2H imidazo[5,1 c] [1,2,4]triazole 3,5(2H) diones.