5250-4 bismaleimide resin is used in high performance polymer matrix composites with high temperature aeronautical applications. This thesis investigated the thermal and oxidative degradation of 5250-4 neat resin powder in argon, air, and oxygen environments. The powder was agedat 163, 177, and 190 C in all environments for at least 250 hours. Isothermal thermo-gravimetric analysis demonstrated that weight loss was negligible for agingin the argon environment, indicating weight loss isthe result of an oxidative process at these temperatures.The 5250-4 powder exhibited an initial period of weightgain before eventually losing weight inboth air and oxygen. The applicabilityof a closedloop oxidation scheme to 5250-4 gravimetric behavior was investigated. Kinetic parameters for the scheme were determined for the AirForce Research Laboratory's polymermatrix composite lifetime prediction modeling efforts.