Highly water-soluble 2 nm anatase nanoparticles were synthesized under mild conditions via a simple, scalable and surfactant-free sol-gel method. The covalent bonding of butoxy groups with surface Ti ions prevents mutual contact of surface hydroxyl groups between particles, leading to the weak inter-linkage of particles in powder. As a result, the obtained powder can be easily dissolved in water just by gentle shaking of container because of the formation of hydrogen bonds between water molecules and surface hydroxyl groups of particles. Originated from the water soluble property of TiO2 nanoparticles, polishable TiO2-SiO2 composite monoliths were prepared for application in UV-shielding. The obtained monolith shows high transparency in visible range and excellent absorption efficiency in UV band. (C) 2013 Elsevier Inc. All rights reserved.