A series of MnEuOx catalysts were prepared by the co-precipitation method and used for selective catalytic reduction of NOx with NH3. It was found that the modification of MnOx catalyst by Eu with a Eu/Mn molar ratio of 0.1 could greatly enhance its SCR activity and broaden its operating temperature window, accompanied by good resistance to SO2 and H2O. From the characterization results of N-2 adsorption, XRD, XPS, H-2-TPR, it could be concluded that the larger surface area resulted from the inhibited crystallization of MnOx, the enrichment of surface MN4+ and chemisorbed oxygen, and the higher reducibility all made a contribution to the high SCR activity of MnEuOx-0.1 catalyst. Furthermore, the results of in situ DRIFTS study revealed the NH3-SCR reactions over MnOx and MnEuOx-0.1 were mainly controlled by L-H mechanism (<150 degrees C) and E-R mechanism (>150 degrees C) respectively, and the contribution of E-R mechanism became more important with increasing reaction temperature. The enhanced NO oxidation and NH3 adsorption should be mainly contribute to the distinguished SCR performance of MnEuOx catalyst in the lower temperature range (<150 degrees C) and higher temperature range (>150 degrees C) respectively. (C) 2016 Elsevier B.V. All rights reserved.