Catalysts synthesized by incorporating CuO (7 wt.% of Cu) on six commercial CexZr1-xO2 mixed oxides (x = 1, 0.8, 0.68, 0.5, 0.15, 0) have been prepared by conventional wetness impregnation method. These catalysts have been screened for CO oxidation in hydrogen streams (CO-PROX) and characterized by means of XRD, BET, Raman, XPS and H-2-TPR experiments. Activity towards CO oxidation in hydrogen streams has been discussed and correlated with the properties of the catalysts. XRD and Raman analysis of the supports show an increase of oxygen defect as Zr content increase. Below 150 degrees C the catalysts reducibility measured by H-2-TPR correlates with ceria content in the support, although an increase of Zr content in the support increases considerably the reduction degree of ceria in the 0-600 degrees C interval. Activity towards CO oxidation in hydrogen streams also correlates with Ce/Cu molar ratio and low temperature reducibility of copper species. Most of the catalysts give complete CO conversion with high selectivity operating with lambda = 2. The most active catalysts is CuO supported on pure ceria, which is able to oxidize completely CO in the interval 96-164 degrees C, with maximum selectivity of 90%. On the other hand, the operation window becomes narrower as Zr content in the supports increases. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.