AbstractNiO‐MoO3‐Al2O3based hydrodesulphurization catalysts appear to be of long term interest in the processing of Athabasca bitumen to eliminate organo‐bonded sulphur and nitrogen‐containing groups. This study employs such a catalyst (NALCO NM 502: 2% NiO, 14.0% MoO3, and γ‐Al2O3) in rate measurements of the vapor‐phase reaction of thiophene with hydrogen using an integral fixed‐bed reactor operated at about atmospheric pressure and in the temperature range, 270 to 350°C. Both power‐law and mechanistic models were fitted to the data; discrimination amongst the later being based upon consistency with physicochemical observations and the power‐law behaviour. The kinetic parameters for these models were contrasted with those obtained by a number of other workers for primarily C