Although a polytetrahydrofuran (PTHF) blend with added glycerin as a crosslinking modifier is an effective binder for improving the performance of a propellant, a burning catalyst is required for the combustion of the ammonium nitrate (AN)/PTHF/glycerin propellant. MnO2 and Fe2O3 are useful burning catalysts for AN-based propellants. The thermal decomposition behaviors of the AN/PTHF/glycerin propellant supplemented with MnO2 and Fe2O3 catalysts, and the catalytic effect of these catalysts on the burning characteristics was investigated in this study. The thermal decomposition behaviors of these propellants depended on the kind of catalyst used. The propellants containing MnO2 burned above 4MPa, while those containing Fe2O3 burned above 0.5MPa. The burning rate increased in the order, (AN/PTHF/Fe2O3)<(AN/PTHF/MnO2)<(AN/PTHF/MnO2/Fe2O3). The improvement in the ignitability and burning rate was dependent on the kind of catalyst used. The burning characteristics of the AN/PTHF/glycerin propellants were improved by the combined effect of multiple catalysts with differing catalytic mechanisms, as compared to the propellant supplemented with any single catalyst.