Ni modified MnOx-CuO/TiO2 catalysts were synthesized by the sol-gel method and investigated for NO-CO reaction. The results showed that 0.05Ni-Mn-Cu/TiO2 (the Ni/Ti molar ratio was 0.05) had the highest NO conversion efficiency with a maximum value of 85.4 % at 350 degrees C, which was 10 % higher than that of Mn-Cu/TiO2. XPS analysis showed that more chemisorbed oxygen formed on the Ni-modified catalyst surface, which could act as active sites for CO adsorption and oxidation. CO-TPD results confirmed that the amount of adsorbed CO on the catalyst surface increased after Ni modification. H-2-TPR results suggested that the Ni-modified catalyst had better redox properties, which favoured the reduction of NO to N2O and N2O to N-2. Furthermore, in situ FTIR showed that CO2 from the production of the NO-CO reaction could be easily formed on the surface of 0.05Ni-Mn-Cu/TiO2, and it indicated that the NO-CO reaction could easily occur after Ni doping. All these factors were responsible for the better catalytic activity of Ni-modified catalysts.