A newly developed real-time kinetic model is presented. The model was used for the characterization of supported metal catalysts' properties in the oxygen isotopic exchange reaction. This model is based on rate equations and includes several elementary processes: adsorption on the metal nanoclusters, reactions on the metal nanoclusters, desorption from the metal nanoclusters, surface and bulk diffusion on/in the oxide support and direct exchange with the gas phase. On the basis of this model, a computer code was developed to determine the kinetic and thermodynamic parameters of the oxygen isotopic exchange reactions. The characteristics of a Rh/CeO2 catalyst were examined in the temperature range between 200 and 450 degreesC. (C) 2003 Elsevier B.V. All rights reserved.