High quality Ba0.5Sr0.5TiO3/SrRuO3 (BST/SRO) heterostructure films have been successfully fabricated by pulsed-laser deposition on (0 0 1) LaAlO3 (LAO) substrates. The bilayer films were both (0 0 1) oriented normal to the substrate surface confirmed by X-ray diffraction analysis. The SRO layer with atomically smooth surface and good metallic behavior serves as not only an ideal bottom electrode but also an excellent template for epitaxial growth of the BST thin film. A parallel-plate capacitor configuration was used to measure the capacitance-voltage and leakage current characteristics of the BST films. The dielectric constant and maximum loss tangent measured at 1 MHz and 300 K were 1058 and 0.0092, respectively. The FOM-factor value reached 49 under the condition of +/-6 V DC bias and 1 MHz. A leakage current density of less than 6 x 10(-7) A/cm(2) was obtained at an electric field intensity of 2 x 10(5) V/cm. These results show the. potential of the BST/SRO heterostructures for microelectronic device applications. (C) 2004 Elsevier B.V. All rights reserved.