Abstract: In this study, LaNiO₃ perovskite catalysts were prepared by citrate method and used for carbon dioxide (CO₂) methanation. The catalysts were activated at different temperatures (400℃~700℃) under the reactant stream. The activation led to the formation of small metallic nickel particles and hexagonal lanthanum oxocarbonate (La₂O₂CO₃). Ni0 was highly dispersed and enveloped by La₂O₂CO₃, which was responsible for the high catalytic activity and stability of the LaNiO₃ perovskite catalysts even at high temperature (400℃~500℃). The X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and H₂-temperature-programmed desorption measurements illustrated that La₂O₂CO₃ generated from the activation might play an important role in the methanation of CO₂.