Barium titanate (BaTiO3) powders with particle sizes about 50 nm in diameter were synthesized using a hydrothermal route. The powders were characterized using various experimental techniques such as XRD, TEM and Raman spectroscopy, and they showed a good crystallinity and homogeneity without heat treatments. Also, Raman spectra showed the presence of the tetragonal phase. In addition, various calcination treatments were made to BaTiO3 powders with the purpose to improve their ferroelectric properties. In general, calcination treatments improved the crystallinity and homogeneity of the samples considerably but did not modify the internal structure of the BaTiO3, which was observed in the Raman spectra. On the other hand, from theoretical calculations were established that the cubic phase should be better dielectric in comparison with the tetragonal phase, but this latter would have better optical properties. However, experimental evidences are indicative that the cubic phase would predominate in the synthesis of the compound.