Polycrystalline BaTiO3 thin films were grown on Ti-covered polymer substrates at 80 degrees C using the microwave-hydrothermal technique. Onset of BaTiO3 formation occurred almost instantaneously at 80 degrees C and complete film coverage was achieved within 2 min. Longer reaction time was necessary for extensive grain growth to achieve dense films. Good quality capacitor films were only achieved at 4 h reaction time but loss tangents were high. Film dielectric constant and dielectric loss values of as-grown M-H films decreased with longer reaction time. Oxygen plasma treatment improved loss tangents to 4% by removal of both absorbed moisture and lattice hydroxyls. (c) 2007 Elsevier B.V. All rights reserved.