The effects of aging under controlled humidity on the thermal decomposition of two nitrate ester/RDX propellants are examined. Propellant samples are artificially aged at 60 degrees C and 70 degrees C at various levels of relative humidity. Differential scanning calorimetry is used to study the post aged samples to determine the activation energy of the peak exotherm and peak temperature of these events. For each humidity level, differential scanning calorimetry is conducted on an aged and an unaged sample that is conditioned to the humidity of the environment to distinguish between aging effects and residual moisture effects. Nitrate ester stabilizer depletions rates are presented as a function of aging and humidity. The results of the study show that moisture level during aging irreversibly alters the activation energy of the primary heat release events and significantly influences the stabilizer depletion rates.