Nanosized TiO2 with controlled crystal phase/structure was prepared by a sol-hydrothermal process using titanium (IV) n-butoxide as a precursor of TiO2. After hydrothermal processing at 200 degrees C for I h, the granulous anatase phase with average crystal size of 5 nm was formed. Upon increasing the heat treatment period to more than 5 h, the rod-like rutile phase with particle size of 19 x 70 nm became predominant. The structure evolution from X-ray diffraction (XRD), particle size/morphology from transmission electron microscopy (TEM), surface area from Brunauer-Emmitt-Teller (BET) analysis, and photocatalytic activity of TiO2 products show strong correlation with the hydrothermal conditions. (c) 2005 Elsevier B.V. All rights reserved.