Electrochemical degradation of 4-chlorophenol was conducted using a reactor with granular graphite as the electrode material. The anode and cathode compartments of the reactor are separated with a Nafion 117 membrane. The reaction can be described with a pseudo-first-order reaction kinetics. The pseudo-first-order reaction rate constants, k, was approximately 0.19 h(-1) at a flow rate of 10 mL/min for all the applied currents. However, the degradation rate increased with flow rate, increasing from 0.13 h(-1) at a flow rate of 5 mL/min to 0.45 h(-1) at a flow rate of 30 mL/min. There was no significant correlation between reaction rate and applied current. The removal of 4-chlorophenol reached about 90% under all experimental conditions after 12 h, and reached 99% after 24 h at an applied current of 300 mA. Using the approach of this study, i.e., electrochemically degrading 4-chlorophenol without supporting electrolytes, could greatly reduce the amount of raw material needed and waste generated and hence, the total cost for treating wastewater containing 4-chlorophenol. (C) 2010 Elsevier B.V. All rights reserved.