The CuO-CeO(2)-MeO(x) (Me = Zr, Ti, Mn, Al; x = 1.5-2) solids were tested in the preferential CO oxidation reaction in hydrogen-rich gas mixtures (PROX). We study an effect of a support (MeO(x)) the CO conversion and selectivity in the PROX reaction showing that monoclinic zirconia (m-zirconia) with low surface area is the most effective support. The optimal catalyst composition was determined by varying copper and ceria loadings over m-zirconia. XRD and XPS studies indicate that a good catalytic performance of m-zirconia supported copper-ceria catalysts may be attributed to the presence of dispersed Cu-containing species that interact with CeO(2) and ZrO(2). (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.