Most industries in Ethiopia are causes for serious environmental problems associated with its polluted wastewater discharge. It is discharged without enough treatment based on the discharge limit set Ethiopian Environmental Protection Authority. Discharging wastewater in this way affects the aquatic environment animals as well as human beings. The objective of this study was determining the removal efficiency of pollutants by electro-coagulation process for treating detergent wastewater. The study was conducted at lab scale by using mono polar Aluminum electrode of electro-coagulation process without any additional chemicals or supporters under variable factors such as reaction time (30min,60min,90min) ,voltage (10v, 20v and 30v) and inter-electrode distance (2cm and 2.5cm) to determine the effective removal of COD, BOD TDS and total phosphorus. Composite wastewater effluent Sample was taken from one detergent manufacturing factory. The detergent wastewater was characterized before and after treatments. The raw wastewater had TDS of 10,049 mg/l .The BOD, COD, total Phosphorus and the pH values of the effluent were on average 216 mg/l, 630 mg/l, 6.509 mg/l, and 10.12 respectively before treatment. The experimental design and data analysis was done by using design expert 13 and SPSS software .The following experimental result was obtained. From the analysis it was found that the optimal removal efficiency of COD 88.42%, BOD 88.39 %, TDS 48.08 % and Total phosphorus 87.45% recorded at voltage of 30v, reaction time 90 min and inter-electrodes distance 2 cm. It was observed that the process of electrocoagulation gives efficient performance in the reduction of detergent pollutants. From the study result of characterization of the detergent wastewater it can be concluded that detergent wastewater pollutants can be efficiently removed using electro-coagulation. Keywords: Coagulation, Composite wastewater, Effluent, Pollutant, characterization.