Here, 2.5 L of solutions of 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide of pH 3.0 have been degraded by electrochemical oxidation (EO) and electro-Fenton (EF) using a recirculation flow plant equipped with a single Pt/air-diffusion or BDD/BDD cell containing electrodes of 20 cm(2) area. In EO, organics were mainly oxidized by (OH)-O-center dot formed at the anode surface from water oxidation, whereas in EF they were also destroyed in the bulk by (OH)-O-center dot generated from Fenton's reaction between added Fe2+ and H2O2 produced at the cathode. In both treatments, the use of a single BDD/BDD cell always allowed larger decontamination due to the higher ability of (OH)-O-center dot at the BDD surface to mineralize organic intermediates. The most potent EF process with this cell gave 59% mineralization with 23% efficiency and 0.42 kWh g(-1) TOC specific energy after 300 min at 0.5 A. The coupling of Pt/air-diffusion and BDD/BDD cells with equal individual current in EF led to similar mineralization degree to that found for the Pt/air-diffusion one at the same total current, but in much shorter time. The effect of current on the mineralization rate, mineralization current efficiency and specific energy of each method was examined. The influence of herbicide concentration on the EF performance of the coupled cell at 2.0 A/2.0 A was also studied and 83% mineralization was obtained as maximal for 276 mg L-1 2,4-D. The herbicide decay always obeyed a pseudo-first-order reaction. A mixture of short-linear carboxylic acids was detected in all final electrolyzed solutions, which were the major organic by-products generated using the single BDD/BDD cell but formed in minor proportion in the EF processes with the Pt/air-diffusion and coupled ones. (C) 2014 Elsevier B.V. All rights reserved.