The reverse water gas shift reaction on molybdenum carbides was studied at 573 K and atmospheric pressure. Molybdenum carbides with various C/Mo atomic ratios were synthesized on gamma-Al2O3 using a vertical tube hot-wall chemical vapor deposition (CVD) reactor in a stream of MoCl5, benzene, and hydrogen at 1000 K and total pressure of 0.13 kPa. The activities of the molybdenum carbide catalysts prepared by the CVD method were compared with those by the temperature-programmed reaction (TPR). The ratio of the C 1s peak of carbidic carbon to the Mo 3d peak of the alumina-supported molybdenum carbide, prepared by changing the benzene/MoCl5 ratio, was determined by XPS spectroscopy. The activities of the CVD and TPR catalysts with the C/Mo ratio of molybdenum carbides for CO2 hydrogenation were discussed. The turnover frequencies of the CVD catalysts were 0.347-0.498 s(-1) and higher than those of the TPR catalysts.