The promoting effect of ceria was studied on the oxidative coupling of methane reaction with Li/Ce/MgO and Na/Ce/MgO. Catalytic tests were conducted with unpromoted Li/MgO and Na/MgO catalysts and showed that samples doped with ceria affected the OCM reaction. In situ XRD results showed growth of MgO and CeO2 crystallites on the Na/Ce/MgO, decreasing the activity and selectivity. The Li/Ce/MgO catalyst presented small and stable crystallites which increased markedly the activity, selectivity and stability. In addition, Diffusion Reflectance Spectroscopy (DRS) results of calcined samples revealed the charge transfer from cerium to oxygen ions, as well as oxygen transfer into the lattice. Different sites may influence the selectivity in C-2 and C-2 yield. The Li/Ce/MgO catalyst presented higher methane conversion and C-2 selectivity than the Na/Ce/MgO catalyst, probably due to different types of involved active site promoted by ceria during the reaction.