La2O3 exhibits good performance for various catalytic applications, such as oxidative coupling of methane (OCM) and dry reforming of methane (DRM), during which coke formation may lead to the deactivation of catalysts. Typically, the reaction between CO2 adsorbed on La2O3 and coke is the rate-determining step of the coke elimination process. This paper describes the influence of Ce addition on the CO2 adsorption and activation over La2O3. Combined with in situ and ex situ characterization and density functional theory (DFT) calculation, we show that Ce addition promotes the formation of bidentate carbonate on La2O3 via tuning CO2 adsorption energy.