The formation of hydrogen during methane conversion on supported Mo nitride catalysts was studied using a flow microreactor at 973 K and atmospheric pressure. The catalysts before and after the reaction were characterized by XRD, temperature-programmed reduction with H-2 (TPR), and temperature-programmed surface reaction with CH4 (CH4-TPSR). Based on the catalytic activity effect of the supports (Al2O3, SiO2, TiO2, and ZSM-5), the ZSM-5 supported Mo nitride catalyst was the most active for hydrogen production. Mo nitride was partially transformed into Mo carbide at 973 K during the CH4 decomposition. The addition of Co and Ni atoms to Mo/Al2O3 promoted the CH4 decomposition activity due to the high hydrogen activation performance by the creation of Co(Ni-) added gamma-Mo2N or Co(Ni)-Mo nitride in nitridation and the formation of Co(Ni)-added eta-Mo3C2 or Co(Ni)-Mo carbide on the surface during the reaction.