Aqueous p-chloronitrobenzene (PCNB) decomposition induced by contact glow discharge electrolysis under various reaction conditions was investigated. Experimental results showed that, at voltage 450-550V and initial concentration 50-500 mg/L, the decay of PCNB can be described by a first-order reaction kinetics of In(C-0/C-t) = 0.029 (I/V)t, where C-0, I, V and C-t denote the initial PCNB concentration (mg/L), applied current (A), solution volume (L) and instantaneous PCNB concentration (mg/L) at treatment time t (min). Major intermediate products such as 4-nitrophenol, 2-chloro-5-nitrophenol, oxalic and formic acids, chloride and nitrate ions were identified by LC/MS and IC, respectively. No chlorophenols present indicated that the dechlorination was easier than denitration from the aromatic ring of PCNB. Formation of hydrogen peroxide during the degradation was observed and the role of Fenton's reaction was examined. Hydroxyl radicals may be the most responsible species for PCNB degradation. (C) 2008 Elsevier B.V. All rights reserved.