Pure cubic phase barium titanate nanoparticles with an average diameter of about 20 nm have been synthesized via a one-step sol-precipitation route at water bath (about 80 degrees C) for 5 h without surfactant and any post-treatment. Based on the observation of transmission electron microscopy and high-resolution electron microscopy images, the assynthesized BaTiO3 nanoparticles exhibit the nature of single-crystal and agglomerate-free. The formation of the singlecrystal BaTiO3 nanoparticles resulted from a diffusion mechanism of Ba2+ ions into the gel at strong alkaline condition. (c) 2005 Elsevier B.V. All rights reserved.