CuO catalysts supported on TiO2 with various compositions of anatase and rutile phase (CuO/R, CuOR7A3, CuOR3A7 and CuO/A) are prepared by a deposition-precipitation procedure, and products are characterized using EPR, TPR, and XPS. The oxidation of CO is used as a model reaction case to test for catalytic activity. Importantly, the type of TiO2 phase present has an effect on the physical, chemical, and catalytic properties of the CuO catalysts. The rutile phase of the TiO2 support (CuO/R) interacts weakly with the CuO and TiO2 support. Cu2+ ions in the supported-CuO are readily reduced to Cu-0 during the CO oxidation reaction. Consequently, CuO/R provides large amounts of oxygen atoms for reaction with CO, which results in the highest catalytic activity among the catalysts examined. The activities of supported CuO catalysts decrease gradually with the decrease in amounts of rutile phase. (C) 2012 Elsevier B.V. All rights reserved.