The activities of copper oxide supported on CeO2, gamma -Al2O3 and ceria-modified gamma -Al2O3 catalysts for the NO + CO reaction at low temperature (200 degreesC) have been investigated. The results show that the activities of the surface-dispersed copper species are greatly enhanced due to the presence of ceria, whether it was used as a support or as the pre-dispersed species on gamma -Al2O3. The activities decrease in the order: CuO/CeO2 > CuO/CeO2/gamma -Al2O3 > CuO/gamma -Al2O3. For the CuO/CeO2/gamma -Al2O3 catalysts, it is shown that NO conversions are not improved significantly with the increasing of CuO and/or ceria loadings, however, the him-over number for the catalysts is found to be strongly relative to ceria loadings. Ey a combination of X-ray diffraction (XRD), electron spin resonance (ESR) and temperature programmed reduction (TPR) results, the states and properties of copper oxide species, as well as the interactions among the surface-dispersed copper oxide species, ceria species and support, are also studied. All the results are tentatively discussed according to the incorporation model proposed previously.