CuO/Ti0.5Sn0.5O2 catalysts were prepared and characterized by high resolution transmission electron microscope (HRTEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible diffuse reflection spectrum (UV-vis DRS), electron paramagnetic resonance (EPR), laser Raman spectra (LRS), in situ infrared spectroscopy (IR), and activity test for CO oxidation. The results indicated that (1) copper oxide is highly dispersed on Ti0.5Sn0.5O2 support below its dispersion capacity of 0.85 mmol Cu2+/100m(2) Ti0.5Sn0.5O2; (2) three types of copper Species are present on Ti0.5Sn0.5O2, which are isolated Cu2+, (Cu-O-Cu)(2+) species, and crystalline CuO, respectively. Of them, the dispersed (Cu-O-Cu)(2+) species are the easiest to be reduced by CO; (3) the catalytic activities of CuO/Ti0.5Sn0.5O2 catalysts are related to the state of copper on Ti0.5Sn0.5O2 support, and the dispersed (Cu-O-Cu)(2+) species are the primary active component. A surface incorporation model was proposed to explain the CuO dispersion of CuO/Ti0.5Sn0.5O2 catalysts. (C) 2012 Elsevier B.V. All rights reserved.