In this research, different concentrations of H2O2 and H2SO4 solutions were used in order to remove the sulfur from high sulfur contented No. 6 fuel oil. In desulphurization experiments, reaction temperature, reaction time, and the concentration of H2O2 and H2SO4 were varied in a range of 20-50 degrees C, 30-150 min, 5-35%, and 0.05-2.00 N, respectively. The ratio of reagent/fuel oil was taken as 10/1 and the stirring speed as 1,000 rpm. According to the results obtained, considering the desulphurization and the organic structure of the fuel, the most appropriate method was found as the H2O2 leaching method. It was barely determined that the highest desulphurization was achieved by H2O2/0.1N H2SO4 leaching method. The optimum process parameters for H2O2 leaching method were found as a concentration of 15%, reaction temperature of 30 degrees C, and reaction time of 60 min; and for H2SO4 leaching method were found as concentration of 0.1 N, reaction temperature of 30 degrees C, and reaction time of 150 min.