[en] Energetic oxetane polymers have shown promise as performance-enhancing ingredients in gun and missile propellants. In order to correctly predict the performance of energetic materials containing these polymers, it is important to have accurate, experimentally determined values for the polymer heats of formation (ΔH_f). In support of a theoretical study on gun propellant performance, heats of combustion were experimentally determined for a series of oxetane polymers and monomers (see below) using combustion calorimetry, and from these, ΔH_f values were calculated. Polymers included BAMO/AMMO, BAMO/NMMO (polyol and TPE), and BNMO/NMMO mixtures. In order to calculate the ΔH_f of the polymers from heat of combustion data, a number of assumptions were made regarding the polymer structure and molecular weight. A comparison of the ΔH_f values for the monomers and polymers were made, and these values were compared to heats of formation measured elsewhere