Photocatalytic decomposition of isopropanol (IPA) presented in gas stream was investigated using a continuous, tubular photoreactor loaded with single TiO2-coated optical fiber under controlled UV periodic illumination. The TiO2 particles were coated on optical fiber through dip-coating process. The introduction of humidity retarded the decomposition of IPA because of the competition between water and IPA molecules for the active sites on TiO2 surface. Operated at retention time of less than one second, about 21% isopropanol was decomposed for experiments conducted with initial isopropanol concentration of 10 ppmv. The apparent quantum yield was increased from 0.78 to 1.28 for experiments conducted with UV-LED as the light source operated at duty cycle shifted from 1.0 to 0.1. At the operation of equivalent duty cycle, both removal efficiencies and quantum yield were also enhanced in the highly frequent periodic illumination by decreasing both light and dark periods. (C) 2013 Elsevier B.V. All rights reserved.