In this work, treatment of poultry slaughterhouse wastewater by electrocoagulation method with aluminum plate electrodes has been investigated. System was operated in batch and galvonostatic mode. Effect of initial pH of the wastewater was predominantly investigated on chemical oxygen demand (COD) removal efficiency but turbidity and oil-grease removal efficiencies were also evaluated. Operational parameters were kept constant at 150 rpm of stirring speed, 1 mA/cm(2) of current density, and 293 K of solution temperature. On the other hand, initial pH of the wastewater was in the range of 2-8. Initial pH of the wastewater was an effective parameter on COD removal efficiency as it is expected. When initial pH of the wastewater was in the range from 3 to 4, it was possible to obtain higher COD removal rates. In this study, when the initial pH of wastewater equals to 3 and current density is 1 mA/cm(2), system gives COD removal efficiency of 85% in 20 min. Meanwhile, system consumes 2.14 kWh/m(3) of energy under above conditions.