Phase pure rutile TiO2 nanoparticles were hydrothermally synthesized using arnorphous TiO2 as a starting material and hydroxyl and carboxyl group-containing organics as modifiers at low temperature and low pH. The prepared rutile TiO2 nanoparticles were of narrow size distribution and small average particle size. The acidity and nonpolarity of the organic modifiers both significantly affected the average particle sizes and particle size distributions of the resulting rutile TiO2 nanoparticles. (c) 2005 Elsevier B.V. All rights reserved.