Ce0.5Zr0.5O2 solid solution was synthesized by a microwave method and used as support for preparing a series of CuO/Ce0.5Zr0.5O2 catalysts. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) and temperature-programmed reduction (TPR), and the results indicated that: (1) the dispersion capacity of copper oxide on Ce0.5Zr0.5O2 is about 0.70 mmolCuO/100m(2)Ce(0.5)Zr(0.5)O(2); (2) there are two kinds of copper species in the catalysts, i.e., dispersed and crystalline copper species. The catalytic activities of CuO/Ce0.5Zr0.5O2 for the low temperature (100 and 125 degrees C) CO oxidation were also tested, which showed that the sample with CuO loading amount of 1.2 mmolCuO/100m(2)Ce(0.5)Zr(0.5)O(2) presented the highest activity. Combined with the XRD and TPR results, it seems to suggest that the main active species in this system should be the surface and/or small particle copper oxide species. (c) 2006 Elsevier B.V. All rights reserved.