Lanthanum titanium oxynitride (LaTiOxNy) thin films are studied with respect to their dielectric properties in low and high frequencies. Thin films are deposited by radio frequency magnetron sputtering on different substrates. Effects of nitrogen content and crystalline quality on dielectric properties are investigated. In low-frequency range, textured LaTiOxNy thin films deposited on conductive single crystal Nb-STO show a dielectric constant epsilon ' approximate to 140 with low losses tan delta= 0.012 at 100 kHz. For the LaTiOxNy polycrystalline films deposited on conductive silicon substrates with platinum (Pt/Ti/SiO2/Si), the tunability reached up to 57% for a weak electric field of 50 kV/cm. In high-frequency range, epitaxial LaTiOxNy films deposited on MgO substrate present a high dielectric constant with low losses (epsilon ' approximate to 170, tand= 0.011, 12 GHz). (C) 2011 Elsevier B. V. All rights reserved.