desulfurization study of gas oil is very important, in order to reduce the resulted pollution from acidic gas SO2, which results by burning the fuel, and to prevent poisoning of sensitive catalysts with sulfur, in subsequent processes, and to prevent corrosion of engines and equipment in refineries. So, refineries have been restricted by very low sulfur content, in their products. Because the hydrodesulphurization did not demonstrate good efficiency in reducing the sulfur and aromatics content to the required limits, it has been to search for alternative or completed methods for it .One of these processes is the oxidation –extraction method, which has been studied in our work. We used hydrogen peroxide as oxidant, and acetonitrile as extraction solvent. We studied Operation conditions in terms the proportion of oxidant and extraction solvent to fuel, and we chose the operation temperatures to suit the specifications of the oxidant and extraction solvent. We studied diesel specifications, which we applied at it the process of oxidation and extraction.