Size-, shape-, and phase structure-controlled synthesis of TiO 2 nanocrystallites has long been one of the main themes in TiO 2 research. Many synthetic techniques have been utilized in the preparation of TiO 2 nanocrystals, among which hydrothermal treatment has been drawing much attention because it directly produces well-crystallized nanocrystallities of a wide range of compositions of crystal phases within a short reaction time. In this study, we carried out hydrothermal growth of rutile TiO 2 rods by using aqueous titanium trichloride (TiCl 3) solutions containing NaCl. Uniform ultrafine rutile TiO 2 particles were obtained, and developed crystal faces were observed by TEM, SEM, XRD, and specific surface area measurements. The obtained rutile fine particles showed high levels of activity for degradation of 2-propanol and acetaldehyde under UV irradiation compared to the activity levels of anatase fine particles (ST-01) developed for environmental clean-up. The surface chemistry of the rutile TiO 2 particles was also investigated. From photodeposition of Pt and PbO 2, we suggest that the (1 1 0) face provides reductive sites and that the (1 1 1) face provides oxidative sites. These results indicate that the crystal faces facilitate the separation of electrons and holes, resulting in improvement of photocatalytic activity.