Abstract: Thermoplastically re-formable plastic sheets with flameproofing means, characterized by a core layer 1-10 mm thick comprised of polyether sulfone or a similar thermoplastic, which core material has a content of at least 0.5 wt. %, preferably at least 2 wt. %, of a flame-protective additive, such as boron trioxide; and said sheet or plate further characterized by outer layers, firmly adhering to and covering the two faces of the core layer, at least 0.05 mm thick and comprised of a thermoplastic having a lower proportional content of the flame-protective additives than the core layer; are particularly useful for interior structures in passenger conveyances, such as airplanes.