We have studied catalytic activity of Pt-doped CeO2 for the oxidation and the dry reforming of methane. The catalyst was prepared by three methods resulting in ceria containing different ratios of ionic Pt versus Pt. We show that these materials have different catalytic activity for methane oxidation and dry reforming and that they are more active when the fraction of ionic Pt is increased. Density functional theory was used to help understand the role of Pt dopant. It was found that the presence of Pt activates the oxygen atoms next to it in the surface layer and this decreases the activation energy for dissociative adsorption of methane (which is the rate-limiting step in the reaction). (C) 2010 Elsevier Inc. All rights reserved.