Ultrathin Al2O3 and HfO2 uniform films of similar to 7.3 nm thick were successfully grown by atomic layer deposition (ALD) on Pt electrodes in situ treated with hydrous plasma. X-ray photoelectron spectroscopy reveals that the Pt surface can be effectively modified to Pt(OH)(2) by the hydrous-plasma treatment. It improves the growth of the oxide films and reduces the leakage in the Al2O3 and HfO2 capacitors. The enhancement of hydrolysis reaction and chemisorption reactivity of the metal precursors on the hydroxylated surface of Pt is responsible for improvements in the growth and electrical properties of the ALD films. (c) 2007 The Electrochemical Society.