The photocatalytic oxidation of phenol, using TiO2 suspensions, has been studied at pilot-plant-scale with solar radiation, at the Plataforma Solar de Almeria (PSA), Spain, and at the laboratory level with Xe lamps, at the University of Barcelona (UB). Two different reactor designs were tested at the PSA: a high concentrating radiation systems (Heliomans) and a low concentrating radiation systems (CPCs). Both were characterized from the point of view of the radiation field. The factors relating the solar radiation arriving at the radiation entering the photoreactors have been determined. Kinetic experiments were performed. In all the cases, the reaction rate shows linear dependence on the square root of the photonic flow entering the photoreactors. The kinetics is the first order with respect to the phenol concentration. The kinetic constants have been determined and compared for all the systems tested (laboratory and pilot-plant scale). The efficiencies of Heliomans and CPCs modules have been compared.