Different Advanced Oxidation Processes (Photo Fenton process, Fenton process and H 2 O 2 /UV) were studied in order to reduce COD from oily compounds aqueous solution using batch system. To get the optimum condition, different variables were studied for each of these processes; such as pH, time, concentration of H 2 O 2 , concentration of oil, concentration of FeSO 4 ·7H 2 O and temperature as parameters. It was found that the optimal pH value for the three processes was 3 and the optimal temperature was 30