Аннотация:Noble metal (M: Pt, Pd, PtPd) supported on ceria system catalysts were investigated. The oxidized and reduced forms of the active component were examined in CO oxidation. All catalysts become more active after a reduction pretreatment, which shifts the temperature of CO oxidation. Analysis of the data obtained from characterization techniques indicates that the strong interaction of metal ions with the support prevent the reduction of the initial MOx to metallic M. The formation of M−ceria interfaces efficiently boosts the oxygen activation during CO oxidation, leading to the formation of chemisorbed O on M and the regeneration of the ceria lattice oxygen, thus greatly improving the catalytic performance.