Résumé : In this paper, results of a research work conducted in four laboratories in the frame of the ECC Research Science Program are presented (Contract ST 2J 0467C(TT)). The preparation of bulk tungsten carbide by reaction of WO 3 with a CH 4/H 2 mixture is studied by TPR. After passivation, the material is characterized by ESCA, X-Ray diffraction, electron microscopy and electron diffraction, physical adsorption (BET using N 2 and Kr) and chemical adsorption of H 2 and CO, TPR under H 2, O 2, and inert gaz. These last studies allowed to evidence the importance of the protection of the material by surface free carbon, in opposition with the high sensitivity of the material to oxygen when "liberated" of its carbon protection. The test reactions used are reforming reactions of hexanes and alkylcyclopentanes. Labelled hexanes with 13C are used for the determination of the reaction mechanisms and comparison with the Pt series metals. Surface free carbon resulting namely from the preparation procedure inhibits all catalytic activity. In situ activation under H 2 at 1073K produces clean hexagonal WC, characterized by a catalytic activity essentially for cracking. This last catalyst is highly sensitive to traces of O 2, that induces important modifications in selectivity. The oxycarbidic type catalyst exhibits selectivities similar to traditional bifunctional catalysts like Pt on zeolites. © 1993.