The degradation of the picloram, a widely used herbicide, has been under-taken by the electrochemical advanced oxidation process, namely electro-Fenton in aqueous solution. This process generates catalytically hydroxyl radicals that are strong oxidizing reagents for the oxidation of organic substances. Degradation kinetics of picloram was investigated. Kinetic results evidence a pseudo first-order degradation, with a rate constant of reaction between picloram and hydroxyl radicals of (2.73 +/- 0.08) x 109 M-1 s(-1). The effect of applied current and catalyst concentration on the degradation and mineralization of picloram was also investigated. The optimum applied current and catalyst concentration values for the degradation of picloram was determined as 300 mA and 0.2 mM Fe3+, respectively. Mineralization of picloram was followed by the total organic carbon (TOC) analysis. At the end of 8 h of electrolysis, 95% of the initial TOC was removed. Several degradation products were identified by using HPLC, LC-MS, GC-MS, and IC analysis. The identified by-products allowed to propose a mineralization pathway for the picloram. degradation. (C) 2007 Elsevier B.V. All rights reserved.