A pilot-scale study was conducted to evaluate Fenton's oxidation with autochthonous iron for treating extracted groundwater contaminated with organic solvents. Based on a previous bench-scale treatability study, a batch reactor pilot-plant system was designed and operated to evaluate the effects of various parameters including pH, iron concentration, hydrogen peroxide dose, and reaction time. Effective system conditions were found to be pH of 3.5, hydrogen peroxide to iron molar ratio of 75/1, and autochthonous iron at an average concentration of 10 mg/l. The data collected demonstrate the effectiveness of Fenton's oxidation using autochthonous iron for treating this contaminated water, with reductions to below method detection limits for many contaminants. This pilot-scale study provided kinetic rate constants for predicting contaminant disappearance, information necessary for designing a full-scale Fenton's oxidation system. (C) 2003 Elsevier Science B.V. All rights reserved.