γ-Al2O3-supported alkaline earth metal oxide samples with different MgO, CaO, SrO and BaO loadings have been prepared by impregnating γ-Al2O3 with alkaline earth metal nitrate solutions and then calcining at 773 K and 1,023 K. The resultant samples have been characterized by XRD, EDS coupled with SEM, CO2-TPD and BET. After preparation of the γ-Al2O3-supported alkaline earth metal oxide samples and impregnation with the liquid catalyst LCPs30, supplied by Axens, the catalytic performance of these catalysts was evaluated in the mercaptan oxidation reaction. Results showed that magnesium base oxide is formed at 773 K and base oxides of calcium, barium and strontium are formed at 1,023 K. Catalysts with higher mole ratios have higher conversions and the basicity increases with increasing base oxide loading in the samples. Furthermore, the conversion of mercaptans increases with increasing atomic number of the alkaline earth metal, excluding MgO, which has the highest conversion compared to the other base oxides.