XRD, LRS, H-2-TPR, and in situ FT-IR techniques were employed to investigate the dispersion, physicochemical behaviors of the Sm2O3 modification for CuO/gamma-Al2O3 catalysts. And the catalytic performance for CuO/Sm2O3/gamma-Al2O3 catalysts was tested by NO-CO reaction. The results indicated that (1) samarium oxide could be dispersed on the surface of gamma-Al2O3 with a dispersion capacity of about 0.625 mmol/100 m(2) and the supported copper oxide could be also dispersed upon the surface of Sm2O3/gamma-Al2O3; (2) the reducibility of copper oxide was inhibited by the presence of samarium oxide, which could be influenced by the loading amounts of Sm2O3 upon gamma-Al2O3 surface; (3) FT-IR results implied that the presence of samarium oxide species made the copper oxide hard to be reduced by CO while enhanced the NO strongly adsorbed; (4) NO-CO reaction could start to react only when both of them were in adsorbed states and the formation of free-like NO3- species was recognized as the intermediates of the reaction; (5) the reaction activity was negatively influenced by the introduction of samarium oxide in CuO/gamma-Al2O3 catalysts. And a possible reaction pathway was tentatively proposed to discuss the NO-CO reaction based on all of these results. (C) 2016 Elsevier B.V. All rights reserved.