Abstract A facile two-step synthesis of 2, 4-dihydro-5-amino-[1, 2, 4] triazol-3-ones is described. Firstly, 1, 3-disubstituted thioureas reacted with bis (trichloromethyl) carbonate (BTC) in the presence of a base such as NaHCO 3 to form the intermediate 4-(arylimino)-1, 3-