CeO2 catalysts modified with earth alkaline metals (M = Mg, Ca, and Sr) were prepared by the citrate method in a M:Ce molar ratio of 1:1. Different analytical techniques including diffuse reflectance Ultraviolet-Visible (DR UV-vis) and diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and temperature programmed desorption of CO2 (TPD-CO2) were used for the characterization of the catalysts. The materials were tested in the oxidative coupling of methane (OCM). The results of calcined samples revealed that the charge transfer from cerium to oxygen ions is shifted when CeO2 is doped, indicating defects on the catalyst surface. A linear correlation was found between the amount of surface basic sites and the ratio of the oxygen species O-2(-) and O-2(2-) to lattice oxygen. This behavior is crucial for the CH4 conversion and selectivity to C2H6 and C2H4 at 700 degrees C. Ca doped CeO2 catalyst revealed the best performance in the OCM, which can be attributed to the similar ionic radii of Ca2+ and Ce4+.