Our calculations with spin-polarized density functional theory and on-site Coulomb interactions ( DFT + U) have showed that ( i) OH groups can facilitate O-2 adsorption on CeO2 even at low OH coverages; ( ii) the OH groups posses a long-range and coverage effects on the O-2 adsorption; and ( iii) the adsorbed O-2 can readily diffuse along the surface Ce atoms in the presence of OH groups, and this may be a large O-2 supply for CO oxidation on the interface of noble-metal/CeO2. We provide the evidence that O-2 is supplied by superoxide species on CeO2 in the presence of OH and can diffuse to the interface of noble-metal/CeO2 for CO oxidation. (C) 2010 Elsevier B. V. All rights reserved.