The photocatalytic activities of nanosized titanium oxide (TiO₂) powders synthesized by hydrolysis of TiCl₄ in several alcohol solutions were investigated for the decomposition of methylene blue (MB) in aqueous heterogeneous suspensions. The effects of the TiO₂ preparation parameters, such as the type of alcohol as solvent, synthesis conditions, and calcination temperature, were examined. Addition of hydroxypropyl cellulose (HPC) as a steric dispersant made it possible to reduce the sizes of the particles to the nanosized range. Titania samples having different crystal structures, particle sizes, and the changes of morphologies were obtained by simply varying the type of alcohol. TiO₂powders were characterized by powder X-ray diffraction (XRD), N₂ sorption analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV/Vis spectroscopy. The anatase content of TiO₂prepared using different alcohols as solvent and calcined at 600℃ increased in the order: n-butanol (100%) ＞ isopropanol (97%) ＞ ethanol (84%) ＞ n-propanol (75%) ＞ methanol (53%). The anatase contents of TiO₂prepared using n-propanol decreased progressively from 97 to 8% over the range of calcination temperatures from 400 to 800℃. The photocatalytic activity of MB degradation is largely dependent on the TiO₂structure. When the rutile content of TiO₂prepared using n-propanol and calcined at 600℃ was 25%, the photocatalytic activity of MB degradation reached a maximum.