Benzo[e]pyrene (BeP) is a widespread polycyclic aromatic hydrocarbon found principally in highly polluted areas. The study of its photochemistry is important because of its possible toxic nature and its potential for phototransformation into biologically active products. We studied the primary photophysical and photochemical degradation processes of BeP, both in solution and adsorbed on silica gel and alumina, acting as models for the atmospheric particulate matter. The radical cation of BeP was characterized as an intermediate species during the photodegradation of BeP in polar solvents and adsorbed on the surfaces. The photoionization process was monophotonic, and once the radical cation was formed, it could react with water or oxygen to yield mainly diones, alcohols, and diols. In alumina, the radical yield was small, in accordance with the low photoreactivity observed on this surface. Two triplet-triplet absorption bands at 350 and 560 nm were observed in the time-resolved spectra of adsorbed BeP and in solution under nitrogen atmosphere. The BeP's triplet state, however, did not play an important role in its photoreaction pathway. The surface's pore size and the coadsorbed water affected the yields and kinetics of the intermediates but not the photodegradation mechanism.