Barium titanate (BaTiO3) particles with book-like and spherical morphology were prepared by using a hydrothermal soft chemical process in the presence of a cationic surfactant. A layered titanate of H1.07Ti1.73O4 with a lepidocrocite-like structure and plate-like particle morphology was used as the precursor. The layered titanate was hydrothemially treated in a Ba(OH)(2)(HTMA-OH) (n-hexadecyltrimethylammonium hydroxide) solution or a Ba(OH)(2)-(HiMA-Br) (n-hexadecyltrimethylammonium bromide) solution in a temperature range of 80 degrees-250 degrees C to prepare BaTiO3. The intercalation reaction of HTMA(+) with the layered titanate promotes the structural transformation reaction from the layered titanates to BaTiO3, while it inhibits the structural transformation reaction to anatase under the hydrothermal conditions. The particle morphology of BaTiO3 prepared by this method dramatically changes with changing reaction conditions. HTMA(+) plays an important role in changing particle morphology in the hydrothermal soft chemical process.