Abstract: Fire barrier composition particularly applicable as an acoustic panel-fire wall structure in aircraft, capable of withstanding a 2,000.degree. F. flame temperature, comprising incorporating a silica-containing material such as silicic acid or the reaction product of silicic acid and maleic anhydride, into a resin, particularly a polyimide resin. The resulting silica-containing resin, e.g. silicic acid-filled polyimide, is then applied to a substrate such as graphite fiber or glass cloth, to form a composite structure, which is then cured. The resulting cured composite when subjected to high temperature, e.g. a 2,000.degree. F. flame temperature, forms silicon carbide and/or silicon nitride, in situ, which stabilizes any char that forms.