Dark blue W18O49 nanorod (NR) with similar to 50 nm length and similar to 4 nm width was synthesized by thermally induced crystal growth process. Pale yellow WO3 NR with the same dimension was also prepared by post-annealing the as-prepared W18O49 NR at 400 A degrees C in air. The W18O49/TiO2 and WO3/TiO2 nanocomposites were then formed by coupling the corresponding NRs and TiO2 by sol-gel process. Under visible-light irradiation (lambda A a parts per thousand yenA 422 nm), the W18O49/TiO2 showed a remarkably high photocatalytic activity in removing gaseous 2-propanol (IP) and in evolving CO2. Its efficiency (6.9 ppm CO2 in 2 h) was more than twice that of the WO3/TiO2, which seems to be caused by a profound visible-light absorbance of W18O49 NR.