Volatile organic compounds (vocs) are harmful air pollutants and are harmful to the skin, central nervous system, kidney and liver. the half life period of these vocs in the atmosphere is about six years. so its necessary for finding the way through science and technology to reduce this vocs concentration at source and atmosphere as well. while much research has been going on tio2 based photocatalytic oxidation (pco) of vocs, its commercial application has remained a challenge. a photocatalytic oxidation (pco) technology for industrial use for controlling vocs at source and in situ ambient air using nano-semiconductor catalysts (tio2) and ultraviolet (uv) radiation (external source and/or solar uv radiation) has been developed. the technology has achieved an overall efficiency of 61 and 77 per cent with one and two reactors (in series).