The kinetics of thiophene hydrodesulfurization is studied on a planar surface science model of a sulfided NiMo/SiO2 catalyst under diffusion-limitation-free conditions in a batch reactor at atmospheric pressure and temperatures between 575 and 675 K. A LangmuirHinshelwood model is used to analyze the data and to derive activation energies and heats of adsorption for thiophene and hydrogen sulfide. The work illustrates the feasibility of kinetic and mechanistic studies using planar models of catalysts which can be prepared and manipulated with procedures available in surface science. (C) 2003 Elsevier Inc. All rights reserved.