Mattos and Aarao Reis [T.G. Mattos, F.D.A. Aarao Reis, J. Catal. 263 (2009) 67] have proposed a kinetic model of catalytic reaction including mass transport on a composite catalytic surface. We show that the boundary conditions for the reaction-diffusion equation they use contradict the prescription of the detailed balance principle for the relation between the rate constants for adsorbate diffusion jumps via the boundary and desorption from different areas, and, for certain parameters, the predictions of their model are qualitatively inconsistent. Quantitatively, their results are inconsistent in the situations where the role of the diffusion jumps from the catalytically active regions to the inactive regions is significant. (C) 2009 Elsevier Inc. All rights reserved.