Degradation experiments using 5 mmol/l ethylenediaminetetraacetic acid (EDTA) solutions at pH 3 were performed in the presence of H(2)O(2) and metals such as Fe(2+), Fe(3+), Cu(2+) and mixtures of Fe(2+)/Cu(2+) and Fe(3+)/Cu(2+) under UV-A irradiation (366 nm)-photo-Fenton and photo-Fenton-like reactions-at different metal/EDTA concentration ratios in order to determine the best conditions for EDTA photochemical removal. Analogous dark reactions were performed for comparison. The reaction course was monitored by both EDTA and TOC determinations. Hydrogen peroxide demand was also evaluated in all cases. In terms of TOC removal, photo-Fenton-like reactions were remarkably more efficient than the analogous Fenton-like reactions. When EDTA was monitored, Fenton-like reactions showed variable performances, being more efficient with EDTA:Fe(2+) and EDTA:Fe(3+) ratios of 1:1. However, in these both cases, reaction rates were lower than the ones obtained under irradiation. Total mineralization ranged from 31% (Cu(2+) system) to 92% (Fe(2+), Fe(3+), Fe(3+) + Cu(2+) and Fe(2+) + Cu(2+) systems) after 4 h of irradiation. Percentage of TOC removal was higher in the presence of iron because some photoactive intermediates were probably formed during EDTA degradation. (C) 2004 Elsevier B.V. All rights reserved.16715967