Photocatalytic decomposition of benzene in an air stream in a continuous TiO2-coated optical fiber photoreactor (OFP) was demonstrated to be effective at relatively short retention times. An increase in TiO2 coating thickness, fiber length and retention time improved the decomposition of benzene; however, excessive TiO2 coating thickness and optical fiber length may hamper the reaction. The UV light intensity distribution on and within the optical fiber was modeled using Snell's law and UV light energy balance. The modeled profile indicated that the UV light intensity decreased rapidly along the axial and radial directions of the optical fiber. A mathematical model combining the continuity equations and Langmuir-Hinshelwood surface kinetics was established to adequately describe the reaction behavior of benzene decomposition in the OFP with only single TiO2-coated fiber.