The degradation of Monuron (3-(4-chlorophenyl)-1,1-dimethylurea) photoinduced by Fe(III) in aqueoussolution has been investigated. The rate of degradation depends on the concentration of Fe(OH)2+, the most photoreactive species in terms of *OH radical formation. These *OH radicals are able to degrade Monuron until total mineralisation. The primordial role of the speciation of Fe(III)-hydroxy complex
investigated in an aqueoussolution containing nitrates and nitrites at 310 nm and 365 nm, respectively. In both NO3− and NO2− conditions, the degradation of monuron followed pseudo-first order kinetics. The intermediate products were identified by GC-MS, and the nitration, hydroxylation and coupling reactions were determined. In addition, the oxidation of the N-terminus group, the substitution of chlorine