Abstract: A thin film barrier structure and process is disclosed, which is seen as particularly useful for use in devices that require protection from such common environmental species as oxygen and water. The disclosed barrier structure is of particular utility for such devices as implemented on flexible substrates, such as may be desirable for OLED-based or LCD-based devices. The disclosed barrier structure provides superior barrier properties, flexibility, as well as commercial-scale reproducibility, through the use of a novel organic/inorganic nanocomposite structure formed by infiltration of a porous inorganic layer by an organic material. The composite structure is produced by vacuum deposition techniques in the first preferred embodiment.