The remote oxidation of organic materials via the gas phase was studied in detail. A TiO2-coated glass plate was faced to an organic film separated by a small gap (50 mum to 2.2 mm), and the TiO2 was irradiated with UV light. As a result, aromatic and aliphatic substances were oxygenated and decomposed to generate CO2 by active oxygen species that were generated at the TiO2 surface and transported in the gas phase. The amount Of CO2 generated during the irradiation with 1 mol of photons was estimated to be 2 x 10(-4) mol for polystyrene oxidation and 3 x 10(-5) mol for polyethylene oxidation. The active oxygen species that oxidizes the organic substrates is most likely to be HO.. Strong evidence for this is the result that the organic materials were oxidized by chemically generated HO. in a similar way.