Cerium is widely known as oxygen storage, but the information about its isotherm adsorption is very limited. In this study, the oxygen isotherm adsorption of cerium promoted Ni-Mo/Al2O3 catalyst and its effect to the oxidative desulfurization process were investigated. The catalyst was synthesized by using wet impregnation method. The metal content was analyzed by using X-ray fluorescence spectrometer. The surface property was characterized by BET surface area and pore volume analyzer. The oxygen adsorption capacity over various loadings of cerium promoted in the catalyst at certain pressure ranges was studied at room temperature condition. The catalyst activity was tested in the oxidative desulfurization reaction. Dibenzothiophene in n-heptane solution was used as the model fuel and H2O2/formic acid as the oxidant. The reaction was conducted at various temperatures and cerium loadings. The result showed that oxygen adsorption capacity and the DBT conversion were increased along with the number of cerium loaded to the catalyst. The highest oxygen adsorption capacity was showed by Ce(3.5%)-Ni-Mo/Al2O3 catalyst of 101.1 μmol/g cat. Moreover, this catalyst could convert 85.0% of DBT to become sulfone at temperature 60°C in the oxidation desulfurization process. © 2023 Author(s).