15 wt.%Ni-12.5 wt.%Co-Al2O3 catalysts promoted with Fe, Mn, Cu, Zr, La, Ce, and Ba were prepared by a novel solid-state synthesis method and employed in CO2 methanation reaction. BET, XRD, EDS, SEM, TPR, TGA, and FTIR analyses were conducted to identify the chemicophysical characteristics of the prepared samples. The addition of Fe, Mn, La, Ce, and Ba was effective to improve the catalytic performance of the 15 wt%Ni-12.5 wt%Co -Al2O3 due to the higher CO2 adsorption capacity of the promoted catalysts. Among the studied promoters, the Fe-promoted catalyst possessed the highest catalytic activity (X-CO2 = 61.2% and S-CH4 = 98.87% at 300 degrees C). Also, the effect of calcination temperature, feed composition, and GHSV on the performance of the 15 wt%Ni-12.5 wt%Co-5wt%Fe-Al2O3 catalyst in CO2 methanation reaction was assessed. The outcomes confirmed that the 15 wt %Ni-12.5 wt%Co-5wt%Fe-Al2O3 catalyst with the BET area of 122.4 m(2)/g and the highest pore volume and largest pore diameter had the highest catalytic activity. Also, the catalytic performance in the methanation of carbon monoxide was studied, and 100% conversion of carbon monoxide was observed at 250 degrees C. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.