CeO2 nanoparticles were prepared by thermal decomposition of cerous nitrate and then used as supports for CuO/CeO2 catalysts prepared via the impregnation method. The samples were characterized by HRTEM, XRD, H-2-TPR, and XPS. The catalytic properties of the prepared catalysts for low-temperature CO oxidation were studied by using a microreactor-GC system. The results showed that the thermal decomposition temperature affected the physical properties of the prepared CeO2 particles, such as particle size and morphology. The loading of CuO in non-crystalline forms on CeO2 supports was different in the CuO/CeO2 catalysts. The loading of non-crystalline CuO was higher on the CeO2 prepared via thermal decomposition at 500 C than those on the CeO2 prepared via thermal decomposition at 400, 600 and 700 degrees C. One part of the non-crystalline CuO in CuO/CeO2 catalysts entered the CeO2 lattice and the other part dispersed over the CeO2 Surface. Calcination temperature had little effect on the catalytic activity when it was lower than 600 degrees C. However, heating the catalysts to higher temperatures (i.e. 800 degrees C) had a significant impact on the catalytic activity because the crystallite size rapidly grows and more CuO and CeO2 phase-separation occurs.(c) 2005 Elsevier B.V. All rights reserved.