Superthermites or metastable intermolecular composites (MIC) are well-known for their excellent combustion characteristics in propellants. Herein, superthermites with three Fe₂O₃ morphologies (rod-like, polyhedral, and olivary) were synthesized. The effects of Al/Fe₂O₃ on the thermal decomposition property of nitrocellulose (NC) were investigated in detail via differential scanning calorimetry (DSC). The results indicate that the catalytic performances of the superthermites are highly relevant to the specific surface area of their corresponding Fe₂O₃. Al/Fe₂O₃ containing rod-like Fe₂O₃ (Fe₂O₃(r)) shows a much improved performance compared with other morphological samples. The values of apparent activation energy (E_a) and thermal ignition temperature (T_beo) of NC-Al/Fe₂O₃(r) were the lowest. This study could provide some directive reference data for the thermal behavior of nitrocellulose-based superthermites.