Organic-inorganic hybrid films were prepared based on a recipe using organoalkoxysilanes' ability to create an inorganic network combined with polymer network formation via radical polymerization of the organic groups. The starting mixtures included different triethoxysilanes (RTES), where the organic substitute (R) was varied from methyl- (MeTES), phenyl- (PTES), octyl- (OTES) to vinyl(VTES). Additionally, films prepared using methacryloxypropyltrimethoxysilane (MPTS) were also investigated. Most of the formulations were enriched with tetraisopropyl orthotitanate (TIP). Based on phase diagrams, the limits of the one-phase liquid regions were determined for the initial (RTES-ethanol-water) ternary mixtures. Non-linear modifications of the refractive indexes versus water concentration, as well as the measured conductivity changes indicate that these apparent homogeneous systems are nanostructured as microemulsions. Based on the results of combined microscale (atomic force microscopy (AFM)) and macroscale (wettability, thermal analysis) investigations, it was possible to observe the internal structure and to explain the measured properties of the final composite films. The high resistance against solvent attack is based on the regular, granular-like structure of the end products. Heating the films (at temperatures above the thermal degradation range for the incorporated organics) forces the inorganic structures to collapse and undergo phase transformations. (C) 2004 Elsevier B.V. All rights reserved.