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A microbial fuel cell with 4-CP as oxidant was established to investigate the feasibility of 4-CP dechlorination in the cathodic chamber of MFC. It demonstrated good performance on electricity generation with P max 12.4 mW/m 2 and CE 22.7%. Besides, 60 mg/L 4-CP could be completely dechlorinated in 45 h in the MFC, and 4-CP dechlorination process and electricity generation process had obvious synergistic effect. microbial fuel cell, chlorophenol, oxidant, dechlorination Microbial fuel cell (MFC) is a device that converts chemical energy to electrical energy with aid of the catalytic reaction of microorganisms [1] . It has been shown that continuous electricity generation can be obtained by using a range of biodegradable fuels including pure substrates such as acetate [2] and organic pollutants in wastewater [3][4][5] . When using anaerobic sludge as inoculants and organic pollutants as fuel in the anodic chamber of MFC, both wastewater treatment and electricity generation could be achieved. Hence, MFC provides a new idea for environmental protection and energy recovery.Researches on oxidants, such as oxygen, potassium ferricyanide, and potassium permanganate [6] , have so far concentrated primarily on their ability of accepting electrons and protons. The effect of cathodic chamber on electricity generation was just to form the pass way for electrons and protons yet. Therefore, if using certain pollutant which had the ability of accepting electrons and protons as oxidant, the cathodic chamber of MFC, as well as its anodic chamber could harvest considerable energy from pollutants. Hence it showed great potential for improving the environmental benefits of the MFC. Few researches on this aspect have been reported so far.Chlorophenol compound is one of the prior controlled organic pollutants in drinking water because of its carcinogenesis. The standard reduction potential of 4-chlorophenol (4-CP) is between +0.5 and +1.5 V, and the standard anode potential in MFC is approximately -0.296 V under typical conditions. Therefore, MFC with 4-CP as oxidant is theoretically feasible. The open circuit voltage could reach approximately +0.8-+1.8 V, similar to that of MFC with oxygen as oxidant [1] .In this study, a two-chamber MFC with 4-CP as oxidant was operated with acetate as fuel to investigate its performance of electricity production and ability of wastewater treatment. Furthermore, the feasibility of the MFC with 4-CP as oxidant was evaluated according to the results of this study.The experimental set-up is shown in Figure 1. The anode and cathode compartments (working volume of 200 mL each) of the MFC were separated by proton exchange membrane (PEM) (Nafion 117, Dupont, USA). Carbon fibres (effective area of 20 cm 2 and mass weight of 0.3 g) were used as electrodes with copper wire connecting them through resistance (245 Ω) and a multimeter (UT70B, UNI-T, HK). The whole reactor was located in a constant temperature room with 25℃.Inoculation sludge was cultivated by incubating an-