Selective CO methanation in the reformate gas over Ni/TiO2 catalyst was carried out. Nickel metal salts (nitrate, sulfate, acetate, chloride and formate) used as a precursor of nickel, calcination temperatures (400-700 degrees C), reduction temperatures (350-650 degrees C) and nickel contents (1-30 wt%) affected to the CO methanation activity and CO/CO2 selectivity over the obtained Ni/TiO2 catalysts. The appropriate nickel precursors were nitrate and acetate and suitable calcination and reduction temperatures were 400-500 degrees C and 450-550 degrees C, respectively. An increase of nickel contents in the Ni/TiO2 catalysts improved to the CO methanation activity. Reverse water gas shift reaction activity was extremely low regardless of nickel contents. As a result, temperature window of Ni/TiO2 catalyst was constant and it could be shifted to desired position by changing nickel content. (C) 2012 Elsevier B.V. All rights reserved.