Zirconia supported molybdenum carbide catalysts exhibited much higher activity for CH4-CO2 reaction than unsupported Mo2C. By lowering the loading amount on ZrO2, deactivation was suppressed completely under the reaction condition of higher CH4/CO2 ratios and excellent activity was maintained. Transmission electron microscopic observation as well as XPS analysis demonstrated that molybdenum carbide was highly dispersed on ZrO2 with strong electronic interaction. Isotopic exchange reaction between CH4 and CD4 showed that the dissociation of methane was significantly retarded by supporting Mo2C on ZrO2, which could be the main reason of high activity and durability of supported catalysts.