In this study Response Surface Methodology (RSM) was employed to investigate the effects of different operating conditions on the removal of hexavalent chromium (Cr(VI)) by the electrocoagulation with stainless steel electrodes. Central Composite Design (CCD) was used for the optimization of the electrocoagulation process and to evaluate the effects and interactions of process variables: applied electric current, electrolyte concentration and application time on the removal of Cr(VI). A sample of metal finishing industry wastewater having a high Cr(VI) concentration of 1470 mg/L was used in the experimental study. The optimum conditions for complete (100%) Cr(VI) removal were established as 7.4 A applied electric current, 33.6 mM electrolyte (NaCl) concentration and 70 min application time. The amount Of Sludge produced under the conditions optimized based on the results from the model was lower than the amount generated by chemical treatment with FeSO4.7H(2)O and non-hazardous in nature. (C) 2008 Elsevier B.V. All rights reserved.