The crystal structure and electrical properties of PZT and BST thin films deposited on various Pt/SiO2/Si substrates by metal-organic chemical vapour deposition and r.f. magnetron sputtering respectively, have been investigated. The surface morphology and crystallinity of Pt films used as the bottom electrode changed with deposition temperature for Pt. The Pt films deposited at 400 degrees C by sputtering have a perfect (111) preferred orientation and a dense surface with a hillock-free morphology,oy. A 130 nm PZT thin film deposited on 400 degrees C-Pt has a dielectric constant of 1300 and a remanent polarization of 32 mu C cm(-2) and a 100 nm BST film has a dielectric constant of 575 and a leakage current density at 2 V of 1.8 x 10(-7) A cm(-2). It is clear that the bottom electrodes are important in determining the preferred orientation and electrical properties of high-dielectric thin films.