Electrocoagulation process with sacrificial aluminium anode was used to separate oil from oily wastewater emulsion. A preliminary experimental study was performed to evaluate the most accurate operating parameters, which are then used for the determination of oil removal efficiency. All experimental design Using response Surface method (RSM) was then applied and oil separation was estimated by measuring turbidity and chemical oxygen demand (COD). An optimal region characterised with low values of turbidity and COD was found. As part of the optimized process. the main effects of the operational parameters were also investigated. The experimental results indicated that electrocoagulation was very efficient, and able to achieve 99% turbidity and 90% chemical oxygen demand (COD) in less than 22 min and Current density of 25 mA cm(-2). Analysis of variance (ANOVA) showed a high variance coefficient (R-2) Value of 0.998, thus ensuring a satisfactory adjustment of the second-order regression model with the experimental data. (C) 2008 Elsevier B.V. All rights reserved.