The ultrasound-assisted co-precipitation method was employed for the synthesis of the Ni -Al2O3 catalysts with different metal loadings for the CO2 methanation reaction. This study indicated that increasing the Ni loading up to 25 wt.% enhanced the surface area, decreased the crystallinity and improved the reducibility of the catalysts, while further raise in Ni loading adversely influenced the surface area. Improvements in catalytic performance were obtained with the raise in Ni content because of enhancing the BET area. The results confirmed that the 25Ni-Al2O3 catalyst with the highest BET area (188 m(2) g(-1)) and dispersion of Ni has the highest catalytic activity in CO2 methanation and reached to 74% CO2 conversion and 99% CH4 selectivity at 350 degrees C. In addition, this catalyst exhibited a great stability after 10 h time-on-stream. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.