Commercial methyl parathion was treated by an electrochemical method using Ti/Pt as anode, Stainless Steel 304 as cathode and sodium chloride as electrolyte. Based on a number of preliminary experiments, a factorial experimental procedure was designed in order to optimize the electrolysis efficiency, in terms of % removed COD and energy consumed kW h per kg of removed COD. The parameters examined were the temperature, the stirring rate of the brine solution, the input rate of the organic material, the current density, the electrolyte concentration and the concentration of Fe2+ ions added. In the experimental range studied, the lower energy consumption measured was 6.61 kW h (kg CODr)(-1) and the higher % COD reduction measured was 86.3%. From a mathematical model, the optimum conditions for the electrochemical treatment of MeP for 2.03 kW h (kg CODr)(-1) were found to be: Input rate of MeP 4300 mg COD min(-1), NaCl concentration 4.5%, 4 g l(-1) of added FeSO4, current density 0.47 A cm(-2), temperature 45degreesC and stirring rate 400 rpm. An experiment was conducted under these optimum conditions which resulted in a satisfactory removal of the organic load (in terms of COD, BOD5). Furthermore, a significant improvement in the COD/BOD5 ratio was achieved, rendering the effluent amenable to further biological treatment.