Dairy industry wastewater is characterized by high chemical oxygen demand (COD) and other pollution load. In the present study, the treatment of simulated dairy wastewater (SDW) was performed by electrochemical (EC) method using iron electrode. Full factorial central composite design (CCD) with four factors namely current density (J), dosage of sodium chloride (NaCl) (m), electrolysis time (t) and pH, with each factor at five levels, was used to optimize the factors for higher COD removal. Operational parameters J, m, t and pH were varied between 61.73-308.64 A/m(2), 0-2 g/l, 10-90 min and 5-11, respectively. Optimum value of J, rand pH were found 270 A/m(2), 50 min, and 7.0, respectively, while m was found to be zero. Optimum COD removal efficiency was found to be approximate to 70%. Physico-chemical analysis of iron electrodes and residues (scum and sludge) has been carried out to understand the EC mechanism as well as to study the disposal aspect of the residues generated during EC treatment. The mechanism of COD removal by EC seems to be a combination of electro-coagulation, electro-floatation and electro-oxidation. (C) 2010 Elsevier B.V. All rights reserved.