Hydrogenation of carbon monoxide was studied over the face centered cubic (fcc) phases of molybdenum and tungsten carbides. Moderately high surface area unsupported molybdenum and tungsten carbides (95 and 52 m(2) g(-1), respectively) were prepared using a temperature programmed synthesis method. The starting oxides were first converted to a cubic nitride by reacting with ammonia, which are subsequently transformed to the carbide in a methane/hydrogen mixture. The presence of the face centered cubic structure was confirmed by X-ray diffraction. The catalysts were tested in a slurry continuously stirred tank reactor (CSTR) at P = 2 MPa, in the temperature range 494-573 K and space velocities that varied from 2.5 to 15 S 1 h(-1) g(cat)(-1). The production of large amounts of carbon dioxide instead of water in the case of molybdenum carbide cat, indicates a high water gas shift activity. In both cases the main hydrocarbon product is methane. (C) 2003 Elsevier Science B.V. All rights reserved.