We are reporting an aqua mediated, one pot microwave assisted synthesis of substituted guanidine derivatives using green chemistry approach. Various substituted guanidine derivatives were prepared by reacting symmetrical and asymmetrical thiourea with different amines under alkaline condition using water as solvent under microwave irradiation (100 W) in moderate yield within 10-95 minutes. All the synthesized compounds were characterized by UV, IR, 1H NMR and Mass spectroscopy.