A morphology-controlled synthesis of barium titanate (BaTiO3) nanostructures from nano-whiskers to nanoparticles, were prepared via a hydrothermal strategy by manipulating the alkalinity and reaction temperature. Initially, the K2Ti4O9 precursors almost remain unchanged in the temperature of 80-160 degrees C at 0.1 M. By increasing the alkalinity and temperature, the BaTiO3 nanostructures initially undergoes ion exchange with precursors while retaining the morphology at the self-sacrifice of K2Ti4O9 nano-whiskers, followed by the formation of BaTiO3 nano-maces. Finally, recrystallization occurs and converts into nanoparticles at 120-220 degrees C at 0.8 M. Also, time-dependent experiment was conducted to probe the ion exchange process. The formation mechanism involves the generation of chemical site inducing the ion exchange process and the dissolution-precipitation reaction. By investigating the synthesis and morphology evolution of one-dimensional BaTiO3 nanostructures, this work may be of great significance for fabrication of other perovskite-type MTiO3 (M = Ca, Sr, Pb). (C) 2014 Elsevier Ltd. All rights reserved.