The catalytic reduction of nitric oxide by H, over the Pt(1 0 0) surface is studied as a function of partial pressures and diffusion of the reactants. Within the mathematical mean field model, originally proposed by Makeev and Nieuwenhuys [A.G. Makeev, B.E. Niewenhuys, Mathematical modeling of the NO + H-2/Pt(1 0 0) reaction: "surface explosion", kinetic oscillations, and chaos, J. Chem. Phys. 108 (1998) 3740-3749], we incorporate the diffusion of adsorbed NO and H and the inhibitory site-blocking effect of adsorbed species N, O, NH, NH3. By considering the influence of non-uniformities or defects, resulting in blocking or enhancing adsorption sites on the catalyst surface, the results show anisotropic front propagation with ellipsoidal shape in agreement with experimental results. The influence of the inert sites on global coupling as they are increased continuously is also studied. (c) 2004 Elsevier B.V. All rights reserved.