Ni bulk catalyst had been studied as an alternative to substitute water gas shift catalyst in our previous study. The properties of catalyst surface have been studied by various characterization methods adding CeO2 to Ni, and the CeO2/Ni catalyst has been applied to the CO removal reaction. with promoting CeO2 to Ni, the performance was enhanced slightly and was expanded to lower temperature. The ability to remove CO could be enhanced by adding CeO2 to Ni, but CeO2 affected methanation rather than water gas shift suggesting that H2 was hydrogenated to CH4 during CO removal reaction resulting in the decrease in overall efficiency of the fuel processor. From the results of XRD, TPR, and XPS, we could suggest that CeO2 changed the surface properties of Ni metal. The _OH functional group played an important role in water gas shift reaction and the movable oxygen on the catalyst surfaces had an effect on methanation reaction. CeO2 on Ni metal weakened the C_O bond, whereas the bond strength of _OH group on the catalyst surface was enhanced by CeO2 addition. Therefore, the reaction rate of water gas shift was relatively lowered in comparison with that of methanation.