similar to 100 mn-sized BaTiO3 powders were prepared by hydro-thermal techniques, and the structural features of the powders were investigated as a function of synthesis temperature and time. The spectral features of (200) XRD peaks and FT-Raman peaks at frequencies of 305 and 710 cm(-1), which are sensitive to the presence of tetragonal BaTiO3, indicate that the nano-sized BaTiO3 powders are dominantly of a cubic phase, but the tetragonal phase is also exhibited at room temperature. The tetragonal and cubic phases exist in the core and shell regions in the powder, respectively; the difference in lattice spacing between the core and the shell regions is 0.061 (A) over circle. and the thickness of the cubic-phased shell region of the powders prepared at 180 degrees C for 24 firs is 3 nm.