Molybdenum carbide catalysts for water - gas shift (WGS) reaction were investigated to develop an alternate commercial LTS (Cu-Zn/Al2O3) catalyst for an onboard gasoline fuel processor. The catalysts were prepared by a temperature-programmed method and were characterized by N-2 physisorption, CO chemisorption, XRD and XPS. It was found that the Mo2C catalyst showed higher activity and stability than the commercial LTS catalyst, even though both catalysts were deactivated during the thermal cycling runs. The optimum carburization temperature for preparing Mo2C was in the range of 640 - 650degreesC. It was found that the deactivation of the Mo2C catalyst was caused by the transition of Modelta+ (IV < δ(+) < VI, MoOxCy), Mo-IV and Mo2C on the surface of the Mo2C catalyst to Mo-VI (MoO3) with the reaction of H2O in the reactant. It was identified that molybdenum carbide catalyst is an attractive candidate for the alternate Cu-Zn/Al2O3 catalyst for automotive applications.