Ferroelectric MgO/(Ba0.8Sr0.2)TiO3 heterostruct ured films have been grown on LaNiO3/Si(100) substrates by an improve d sol-gel technique. The dielectric constant and the leakage current of (Ba 0.8Sr0.2)TiO3 films have been modified by MgO insert ion. The dramatic reduction in the leakage current has been attributed to the mi nute solid solubility of MgO in the (Ba0.8Sr0.2)TiO3 lattice and the high resistance of the MgO layers.