We have found molybdenum-catalyzed ammonia formation using simple and commercially available monodentate and bidentate phosphines as auxiliary ligands with a simple and convenient procedure. Molybdenum complexes generated in situ from [MoI3(THF)(3)] and the corresponding phosphines such as PMePh2 and 1,5-bis(diphenylphosphino)pentane worked effectively toward ammonia formation.