The dielectric constant, elastic modulus and reliability of the pure silica-zeolite composite film which was formed by self-assembly of porous silica having hydrothermally crystallized zeolite nanoparticles. Fourier-transform-infrared spectroscopy indicated that Si-OH and O-H bonds decreased by zeolite formation, resulting in the decrease of the dielectric constant. Silylation hardening by 1,3,5,7-tetramethylcyclotetrasiloxane (TMCTS) vapor treatment could decrease the dielectric constant due to the decrease of Si-OH and O-H bonds. The elastic modulus of 7.03 GPa and the dielectric constant of 1.94 were achieved for the meso-porous silica-zeolite film by silylation hardening. Furthermore, mean-time-to-failure (MTF) lifetime of time-dependent dielectric breakdown (TDDB) is longer than ten years at 125 degrees C under the electric field of 3.4 MV/cm. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3570582] All rights reserved.