This report presents time-temperature flexural data obtained on reinforced plastics to establish standard elevated temperature exposure and test procedures. This program included the investigation of: time-temperature properties, the most satisfactory short time exposure period, and cycling type exposure which included simulation of service conditions. Based on the mechanical property data obtained utilizing typical reinforced plastic materials it was determined that the most important criteria involved in elevated temperature determination of mechanical properties were time at temperature and cyclic exposures. Optimum methods and exposure procedures are recommended for short and long time elevated temperature structural studies of reinforced plastic materials.