CuO supported on gamma-Al2O3 and Mn2O3 modified gamma-Al2O3 was prepared and characterized by XRD, UV-vis, XPS,TPR and in situ adsorption IR. NO reduction by CO over these catalysts was also investigated. For the modification of gamma-Al2O3 by Mn2O3, manganese oxide was highly dispersed on gamma-Al2O3 surface to form a monolayer with a dispersion capacity of about 1.0 mmol Mn3+/100 m(2) gamma-Al2O3 corresponding to 8.1 wt.% of Mn. For supported copper oxide, CuO dispersion capacity was 0.75 mmol Cu2+/100 m(2) gamma-Al2O3 on gamma-Al2O3. and increased to 1.1 mmol Cu2+/100 m(2) gamma-Al2O3 on 1.0 MnOx-gamma-Al2O3, indicative of an elevated CuO dispersion capacity upon Mn2O3 modification. For NO reduction by CO, the addition of manganese oxide generally enhanced NO conversion and N-2 selectivity. Furthermore, the catalyst with the loading amounts of Cu and Mn of 0.6 mmol and 0.3/100 m(2) gamma-Al2O3 respectively exhibited the most prominent catalytic efficiency among the tested catalysts in terms of NO conversion and N-2 selectivity. Additionally, these catalysts showed stable NO conversion and N-2 selectivity. (C) 2010 Elsevier B.V. All rights reserved.