Petroleum refinery wastewater contain soluble petroleum hydrocarbons in water such as phenol, benzene, amonia that is not removed by physical method. Various methods have been considered for treatment of petroleum refinery wastewater in recent years, such as biological, phothocatalytic and electro-photo phenton method. Microbial fuel cells (MFCs) represent a promising candidate as a new method for wastewater treatment, because of high efficiency, electricity generation, and low cost in comparison with other methods of wastewater treatment that can be used for treatment of petroleum refinery wastewater. In MFCs, microorganisms act as biocatalyst to catalyze the oxidation reactions of organic matters in the anodic chamber. In general, microbial fuel cells consist of anaerobic anodic chamber and aerobic cathodic chamber that may be separated by a selective membrane limiting diffusion of oxygen into the anode chamber. Electrons and protons produced from oxidation reactions are traorted to cathode from different paths and electrochemically react with cathodic electron acceptor. In this project, treatment of Isfahan petroleum refinery waste water (COD = 213.9 mg/l, PH =7.1) was investigated in double chamber microbial fuel cell (non-catalyzed graphite electrodes) having a total volum of 350ml anode and cathode chamber.The MFC was inoculated with activated sludge was collected from anaerobic biological treatment wastewater reactors of Isfahan petroleum refinery. After injection of 300 ml fresh wastewater and 50 ml mixed culture to anode chamber maximum power production with oxygen cathodic electron acceptor in cathode chamber was 0.09 w/m 3 at 33?. Decreasing the temperature from 33? to 24? reduced the maximum power density to 0.057 W/m 3 . COD of treated wastewater was measured after different batch times. COD removal of petroleum wastewater after 44 hr was 49%, 44% and Coloumbic efficiency was 6%, 4.7% at 33? and 24?, respectively for 200? external resistant that indicate the COD removed by the electricity generation is very small. For recovering more electrical power, permangenate used as effective cathodic electron acceptor. Its high redox potential offers the possibility of appliction in a microbial fuel cell system to estabilish a high potantial difference between the anode and the cathode. Maximum power production at 33? using permangenate with initail concentration of 0.03, 0.06, 0.13, 0.2 g/l was 0.19, 1.55, 2.66, 2.72 W/m 3 respectively. Moreover, the internal resistant of the microbial fuel cell with 0.2 g/l permangenate as cathodic electron acceptor (500?) redused relative to MFC with oxygen electron acceptor (1300?). Infact internal resistance is slope of polarization curve. COD removal of petroleum wastewater using permangenate after 44 hr was 78% and Coloumbic efficiency was 25.4% at 33? for 200? external resistant (maximum Current, 2.1 A/m 2 ). Moreover, COD removal was 57.7% for 3000 ? external resistance at 33? (maximum Current, 0.357A/m 2 ) that indicate the COD removed by the electricity generation is more than in relative to oxygen electron acceptor MFC. The amount of permangenate consumed per unit of removing COD was 1.68, 1.32 kg KMnO 4 /kg COD at 33? and 24?, respectively. With decreasing surface cathode from 10 cm 2 to 5 cm 2 maximum power density decreased from 2.4 W/m 3 to 1.6 W/m 3 using permangenate as cathodic electron acceptor at 33?. Keywords: petroleum refinery waste water, microbial fuel cell, chemical oxygen demand, potassium permangenate