This work investigated the effect of the defect structure referred to as Ti3+ present in titania support of supported titania on characteristics and activity of the Co/TiO2 catalyst. Titania supports were prepared by sol-gel and then calcined under N-2 plus increasing the amount of O-2 to change the surface defect concentration. The surface defect of titania support was increased by increasing the oxygen percent in feed during the calcination process. This defect was monitored using the CO2-temperature program reduction (CO2-TPD) and electron spin resonance (ESR). Cobalt was impregnated onto titania supports containing different defect structures. XRD, SEM-EDX, TPR, and H-2-chemisorption were used to characterize Co/TiO2. It was found that dispersion of cobalt and reducibility increased with the amount of surface defect present. Based on high dispersion and reducibility results this catalyst showed a high conversion for methanation without changing CH4 selectivity.