In this study, nickel (Ni) and cobalt nickel (Co/Ni) supported on alumina were successfully synthesized by a facile electrolysis procedure and were tested for CO2 methanation. By applying the Ni/Al2O3 catalyst, CO2 conversion reached up to of 10 mu mol/g.s, which is 1.4 times higher than Co/Ni/Al2O3, followed by the parent Al2O3. The addition of Co into Ni/Al2O3 has formed spinel phase in Co/Ni/Al2O3, as well as caused a slight increase in the basicity, which directed to the higher formation of formate species as observed by in-situ CO2 + H-2 FTIR study. Both catalyst followed the dissociative mechanism during the CO2 methanation. However, bigger metal particles in Co/Ni/Al2O3 caused slower hydrogen dissociation compared to Ni/Al2O3, leading to lower yield of CH4. The optimization study via the response surface methodology (RSM) showed that the yield of CH4 was significantly affected by reaction temperature, followed by treatment time, the ratio of H-2:CO2 and lastly the gas hour space velocity (GHSV). (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.