The ultrasound assisted oxidative desulfurization (UAOD) of dibenzothiophene (DBT) in model diesel fuel was investigated using deep eutectic solvent (DES). The choline chloride/p-toluenesulfonic acid DES was synthesized by simple mixing of raw materials at 85 °C. DES was used as both extractant and catalyst in the UAOD process. To find the optimal values of the parameters influencing the removal of DBT, response surface methodology (RSM) based on Box-Behnken experimental design (BBD) was applied. Independent parameters including time, DES and oxidant volumes were optimized and the percentage of sulfur removal reached as high as 97.53% under optimal conditions of 121.168 s, 0.203 of VDES/VFuel and 6.42 of n(H2O2)/n(DBT). The model was successfully validated under these conditions. The time of the UAOD process was also compared with the time of the conventional oxidative desulfurization. The results indicated that UAOD process was completed in a significantly shorter time.