We study the electronic and catalytic properties of FeO2 adsorbed on a MgO(1 0 0) surface which shows potential as a novel low-cost and low-temperature CO nanocatalyst in an overall exothermic reaction. The CO oxidation may be separated into two steps, namely (1) oxidation of CO by the metal oxide leaving a reduced metal oxide and (2) oxidation of the reduced metal by oxygen to regenerate the active metal oxide. It is found that CO and O-2 adsorption energies are the driving force for the CO oxidation by providing the energy required to surmount the activation energies along the reaction path. (C) 2014 Elsevier B.V. All rights reserved.