Water-soluble anatase TiO2 nanocrystals (NCs) were synthesized by a simple sol-gel method. The reaction time is greatly reduced even under mild conditions. High-resolution transition electron microscopy (HRTEM), X-ray diffraction (XRD) and UV-vis were used to characterize the synthesized NCs and proved that the NCs are anatase phase and about 2 nm with near spherical shape. Surface photovoltage spectroscopy (SPS) experiments show that the synthesized anatase NCs have good photovoltaic properties compared with that of poly(vinyl pyrrolidone) (PVP) coated NCs synthesized by the similar method. (C) 2007 Elsevier Inc. All rights reserved.