In this research methylene blue (MB) was use as a pollutant to investigate the capability of dye degradation of photocatalytic (UV/TiO2) and photoelectrocatalytic (UV/TiO2/bias) reaction and also the condition for UV/TiO2/bias process was optimized The photocatalytic process with bias potential was conducted in aqueous supporting electrolyte and with a proton exchange membrane (Nafion 117) Comparing with the general use of aqueous electrolyte (e g NaSO4 KCl or NaCl) in photoelectrocatalytic process this study was focused on the application of proton exchange membrane as a solid electrolyte for the photoelectro-catalytic decomposition of MB The degradation of MB was experimentally studied by a varied reaction condition (i e solution pH value UV light intensity initial dye concentration gas introduction supporting electrolyte concentration and bias potential) Degradation of MB was enhanced in UV/TiO2/bias process as compared to that carried out in UV/TiO2 process especially as the Nation membrane was applied (UV/TiO2/Nafion process) The photodegradation rates could also be boosted by increasing the concentration of supporting electrolyte concentration of dissolving oxygen and UV light intensity in UV/TiO2/Nafion process the i ate constants of MB degradation increased as increasing bias potential to a certain level and then it leveled off The suitable bias potentials for experiments conducted at pH 5 3 and 7 0 were found to be 0 5 and 0 6V respectively (C) 2010 Elsevier B V All rights reserved