The development of new electrochemical and photochemical methods for the decontamination of natural water containing significant concentrations of aromatic pesticides is described. The electrochemical method is based on the electro-Fenton process, i.e. the simultaneous reduction Of O-2 and Fe3+ ions. Hydroxyl (OH.) radicals are electrosynthesized in aqueous solutions, followed by complete mineralization of the initial pollutants. The photochemical methods involve either a direct photo degradation reaction of pesticides by UV light, or indirect photodegradation processes including H2O2 photolysis or photo-Fenton reagents (H2O2/Fe3+). Examples of the application of these methods to chlorophenoxy acid herbicides and four aromatic pesticides (bendiocarb, pirimiphos-methyl, coumatetralyl, chlorophacinon) in aqueous media are given. Environmental applications are also presented. The performances of electrochemical and photochemical methods are compared.