The dry-methane reforming (DMR) behavior of Co-Mo and Ni-Mo carbide catalysts has been studied in order to establish the effect of the cobalt or nickel content of molybdenum carbide DMR catalysts. The results indicate that incorporating cobalt into the Mo2C structure at a Co/Mo ratio of 0.4, i.e. a Co0.4Mo1Cx catalyst, gives a DMR activity and stability that are markedly higher than those of Mo2C Catalysts. With respect to the Ni-Mo carbide catalysts, a Ni/Mo atom ratio of 0.2 (i.e. an Ni0.2Mo1Cx Catalyst), gives the maximum synergistic interaction between Ni and Mo. However, higher molar ratios decrease the promoting effect and facilitate the phase separation of the promoter. These results are proved by X-ray diffraction. X-ray photoelectron spectroscopy. Fourier-transform infrared spectroscopy and N-2-adsorption studies, and are also reflected in the poor catalytic stability of both the Co-Mo and the Ni-Mo carbide catalysts. (C) 2009 Elsevier B.V. All rights reserved.