In this work the effect of Ce/Zr ratio on Pt/CexZr1-xO2/Al2O3 catalysts prepared by impregnation was studied. The samples were tested for the partial oxidation of methane and characterized by different techniques such as temperature-programmed reduction, oxygen storage capacity, and infrared spectroscopy of adsorbed CO2. The platinum dispersion was determined through the cyclohexane dehydrogenation and the results showed that the metallic dispersion was approximately the same for all samples. However, among all the catalysts tested the sample Pt/CeO2/Al2O3 and Pt/Ce0.50Zr0.50O2/Al2O3 presented the higher activity and stability for the methane partial oxidation reaction. This result could be due to a good distribution of the ceria-based oxide on the alumina surface, a good reducibility and a high oxygen storage capacity verified for these samples. All these characteristics contributed to the removal of coke formed on the active sites formed during the reaction, avoiding the sample's deactivation. (c) 2005 Elsevier B.V. All rights reserved.