This study focused on the effects of 2,4-dichlorphenol (2,4-DCP) initial concentration, initial pH value, applied current density and supporting electrolyte in water on 2,4-DCP degradation over Er-chitosan-PbO2 electrode in a batch reactor. The results showed that higher initial 2,4-DCP concentration promoted the instantaneous current efficiency (ICE) and average current efficiency (ACE), however, 2,4-DCP degradation rate was inhibited although the removal amount was increased. In the range of initial pH between 3.3 and 12.5, both the highest and the lowest pH conditions favored 2,4-DCP degradation. With the increase of applied current density (1-10 mA/cm(2)), 2,4-DCP degradation efficiency increased initially, however, no significant change was observed afterwards. An acidic condition and higher applied current density were more beneficial to COD removal. The removal efficiency of 2,4-DCP was increased when NaCl was used as the supporting electrolyte instead of Na2SO4 or NaNO3. The increase of supporting electrolyte (NaSO4) concentration (0.01-0.05 mol/L) advanced 2,4-DCP degradation, COD removal and ACE. However, obvious inhibitory effect was exhibited when NaSO4 concentration increased over a certain value (0.1 mol/L). The activity of Er-chitosan-PbO2 electrode for 2,4-DCP degradation kept steady after repeated use. (C) 2010 Elsevier B.V. All rights reserved.