Cu-Mn mixed oxides were prepared by a co-precipitation method and applied for low temperature NO reduction with NH3 in the presence of excess oxygen. Effects of [Cu]/[Mn] ratio and calcination temperatures on NOx conversions were investigated. Cu-Mn oxide catalysts containing small amounts of copper showed the complete NOx conversion in a wide range of reaction temperature from 323 to 473 K. This catalyst showed a reversible deactivation due to the presence of water vapor and SO2. Different catalytic activities of Cu-Mn mixed oxides could be attributed mainly to surface areas and the crystalline nature. (c) 2005 Elsevier B.V. All rights reserved.