The impact of nanoparticle size effects in heterogeneous catalytic kinetics over supported metal catalysts is discussed taking Into account different activities of edges and terraces Kinetic equations for the Eley-Weal mechanism as well as for the two-step sequence were derived analyzed and compared with experimental data for ethene hydrogenation Quantitative description for selectivity in a consecutive reaction of pyrrole hydrogenation/ring opening as function of the metal cluster size is provided demonstrating good correspondence between theory and experiments (C) 2010 Elsevier Inc All rights reserved