The photocatalytic oxidation of 2,4-Dichlorophenol (DCP), using TiO2 suspensions under solar radiation, has been studied at pilot-plant scale at the Plataforma Solar de Almería (PSA). Two different reactor designs were tested: a medium concentrating radiation system called a Parabolic-Trough-Collector Reactor, PTCR, equipped with two motors (azimuth and elevation) to adjust the position of the module perpendicular to the sun, and a low-concentrating radiation system, the Compound-Parabolic-Concentrator Reactor, CPCR, facing south and inclined 37 degrees. Substrates were dissolved in water to required mg L−1 levels in a reservoir tank. In both cases, 0.2 g L−1 of the suspended TiO2 catalyst was used in a 250 L solution of the contaminant, which was recirculated through the photoreactors using a centrifugal pump and an intermediate reservoir tank. The advantages and disadvantages of the two types of photoreactors in DCP oxidation are compared and discussed. The strong potential of photocatalytic peroxydisulphate-assisted degradation in high DCP concentrations was demonstrated in both systems, and chemical actinometry (the decomposition reaction of oxalic acid by radiated uranyl salts) in the CPC reactor is compared with the results obtained in the PTC.