A study of the CO oxidation reaction was conducted on a CuO-CeO(2) catalyst, with a copper content of 20 at%. The stability, activity and selectivity of this sample were evaluated in the absence of H(2) and also under PROX conditions (i.e. in great H(2) excess). The influence of the reaction temperature and the feed composition was also analyzed. It was found that water and CO(2) have a negative effect on the catalytic activity. Except for the undesired oxidation of hydrogen, the occurrence of other lateral reactions that could be present in the PROX reactor can be discarded. A kinetic study was carried out in order to fit a classical power-law expression for CO oxidation rate. Although this mathematical expression gave a good fit in limited concentration ranges, it was found that the partial reaction orders depend on the reactant molar fractions. (C) 2009 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.