BaTiO3 nanoparticles were sonochemically synthesized in ethanol-water mixture solution at low temperature. Different growth mechanisms of the BaTiO3 particles were identified in aqueous solution and ethanol-water solution under ultrasonication. Nanocrystals firstly formed and then oriented aggregated into large particles in aqueous solution under ultrasonic irradiation. Compared to the synthesis in aqueous solution, the BaTiO3 nanoparticles could be prepared at low temperature in ethanol-water solution. Furthermore, the oriented aggregation of BaTiO3 nanocrystals was suppressed and the BaTiO3 nanoparticles grew up from the Ti-based precursor through a dissolution-precipitation process. (C) 2011 Elsevier B.V. All rights reserved.