Epitaxial thin films of MgO were grown on Si(100) with a cube-on-cube relationship as a buffer layer for the growth of ferroelectric BaTiO3 thin films by RF magnetron sputter deposition. Partially (001) or (100) textured BaTiO3 thin films were obtained on Si(100) with the MgO buffer layer. On the other hand, randomly oriented BaTiO3 thin films with large-scale cracks were prepared without the MgO layer. The comparison of the crystallographic orientation, morphology and dielectric properties of the BaTiO3 thin films on Si(100) with and without the MgO layer revealed the favourable influence of the MgO-buffer layer on the growth of BaTiO3 thin films on Si(100) substrates.