This study aimed to evaluate the performance of an electrocoagulation reactor (EC) and investigate its efficiency in heavy-polluted industrial wastewater treatment. The electrocoagulation (EC) reactor has been experimentally evaluated using aluminum (Al) electrodes and connected to a direct current power at various applied voltage levels at room temperature in a relatively limited reaction time. The treatment performance efficiency of the selected dominant EC operating parameter groups: pH, reaction time, inter-electrode distance, and applied voltage was investigated. The results demonstrate that the applied voltage to the electrocoagulation reactor was the most significant factor in pollutant removal. The maximum total suspended solids (TSS), Biochemical oxygen demand (BOD), and Chemical Oxygen demand (COD) removal efficiencies up to 87%, 88%, and 90% respectively were obtained at 20 mm inter-electrode distance with pH: 7 when the applied voltage was 55V in 60 treatment minutes. Overall, the removal performance efficiencies obtained under the study’s conditions show that the electrocoagulation system has a significant efficiency to treat indusial wastewater effluents with high pollutant contents.