Molybdenum carbides supported on TiO2 or ZrO2 were prepared by a temperature-programmed reduction-carburization method using mixtures of hydrogen and hydrocarbon (methane or ethane). All of the materials exhibited molybdenum carbide with a cubic crystallographic structure. The carbon content and the MoC lattice parameter increased with the increase of the hydrocarbon percentage (5-40%) and temperature (600-800 degrees C) during carburization. All catalysts were significantly active in the hydrogenation of succinic acid to butyric acid and gamma-butyrolactone. For the first time, a correlation between the degree of carburization and the catalytic activity for succinic acid hydrogenation was established. The selectivity depends strongly on the support. MoC/TiO2 favored the formation of butyric acid, while MoC/ZrO2 and bulk MoC generated gamma-butyrolactone primarily. The stability of MoC/TiO2 up to 50 h on stream in a continuous reactor was demonstrated, showing the interest of carbide catalysts for future biorefinery processes.