Titanium films were deposited in a vacuum on thermally oxidized silicon. When the titanium/silicon-oxide/silicon structures were heated in oxygen to temperatures of 800-1000 degrees C, titanium oxide films grew on the silicon substrates by a solid-state reaction that involved titanium atoms substituting silicon atoms in silicon oxide. The thickness of the titanium oxide films increased proportionally to that of deposited titanium films. The dielectric constant, resistivity, and breakdown field strength were significantly influenced by treating temperature. The 1000 degrees C-prepared TiO2 films had the dielectric constant of (15-25) epsilon(o), the resistivity of 10(10) Omega cm, and the breakdown field strength around 10(6) V/cm.