A novel integrated process is proposed for the catalytic oxidative desulfurization of fuel oil, in which the oxidant H 2 O 2 is in situ generated by oxidizing 2-propanol with oxygen, and its feasibility is evaluated in terms of the S-conversion of 3-methylthiophene (3-MT), benzothiophene (BT), and dibenzothiophene (DBT) in octane under varying conditions. The catalysis of [π-C 5 H 5 NC 16 H 33 ] 3 [PW 4 O 16 ] is found to be much superior to H 3 PW 12 O 40 and [(C 4 H 9 ) 4 N] 3 [PW 12 O 40 ] due to its good dispersivity in oil and adsorptivity for S-compounds. Some influencing factors for the S-conversion were studied, viz., time, temperature, various S-compounds, and the amount of 2-propanol, initiator, oxygen, and catalyst. All factors that favor the production of the 2-propanol radicals affect the desulfurization rate remarkably. Both BT and DBT can be removed efficiently at mild conditions (1.4 MPa O 2 , 90 °C) in 6 h with S-conversion above 96%, and the resulting sulfones can be separated via settling or filtration.