The photocatalytic degradation of organic compounds using titanium dioxide is a promising method for the clean up of polluted water, especially if the sun is used as the light source. In this paper a novel double-skin sheet reactor made of Plexiglas® , able to use diffuse as well as direct sunlight, is introduced. To characterize this novel photochemical reactor for solar water detoxification, degradation experiments were performed using dichloroacetic acid as a model compound and varying the type of catalyst and its concentration. Moreover, the content of molecular oxygen of the suspension was varied systematically. Photonic efficiencies up to 13 percent were achieved in these experiments in very good agreement with those of corresponding experiments performed under idealized laboratory conditions. Photocatalytic detoxification experiments with ground water contaminated with nitro aromatic compounds from a World War II ammunition plant proved that this reactor can indeed be employed for the solar detoxification of realistic contaminated water.