Treatment of an industrial wastewater containing Z1 oil from Iran Valve Gas company was performed by electrocoagulation using Al and Fe electrodes in this study. Z1 oily emulsions are employed, primarily to reduce the heat generated and the friction caused by contact of the tool on the work piece. In this research effects of five parameters of pH, operation time, current density, electrodes material and gap of electrodes on removal of COD and turbidity efficiency were studied. The range of parameters were obtained by primarily experiment and were pH (4-8), operating time (20-60 min) and current density (208.33-625 A/m 2 ). In order to evaluate the effect of three parameters pH, current density and operation time experiment were designed by experimental design and RSM method in 5 level and data were analysed by ANOVA. All experiments were performed at room temperature and to ensure the results, the experiments were repeated at least twice. Obtained models for COD and turbidity removal efficiencies by RSM method for both electrode Al and Fe are Quadratic. For COD and turbidity removal, R 2 coefficient for Al electrode are respectively 0.86 and 0.78 and also this coefficient for COD and turbidity removal efficiencies by Fe electrode, respectively are 0.93 and 0.96. For COD and turbidity removal, F-value coefficient for Al electrode are respectively 6.83 and 3.93 and also this coefficient for COD and turbidity removal efficiencies by Fe electrode, respectively are 15.59 and 27.57. Optimal values for COD and turbidity removal efficiencies by Al electrodes are respectively 93.50 and 99.92% that are corresponding to pH (4.88), operating time (52.8 min) and current density ( 482.55 A/m 2 ). Optimal values for COD and turbidity removal efficiencies by Fe electrodes are respectively 93.16 and 98.79%. Optimal parameters obtained for this electrode are pH (6.70), operating time (59.8 min) and current density (625 A/m 2 ). Experimental results by optimal parameters delivered by Design Expert, for COD and turbidity removal efficiencies for Al electrodes respectively are 93.23 and 99.40%. These results for Fe electrodes by its optimal parameters, for COD and turbidity removal respectively are 89.56 and 96.90%. Optimal values obtained for COD and turbidity removal efficiencies have conformity with actual values derived by experiments. Accordig to derived values the best range for pH for Al electrode is 4-6 and for Fe electrode is 6-8. Also the maximum COD and turbidity removal efficiency derived at high value of operation time and current density. Results show that Al electrodes are more effective than Fe ones for treating Z1 oily wastewaters. Optimum electrodes distance for both Al and Fe electrode were 2 cm. Results show that electro-coagulation is an appropriate method to remove turbidity and COD from Z1 oily wastewater. Keyword : Wastewater treatment Z1 oil, Electro-coagulation, Al Electrodes, Fe electrodes, Design of experiments, RSM method