In this study, mesoporous α-Fe2O3 catalysts were synthesized from mesoporous silica SBA-15 as the hard template and iron nitrate as the iron oxide source via nanocasting strategy. In order to access the highest loading of iron oxide in the template pores, different weight ratios of Fe(NO3)3·9H2O/SBA-15 were used in the pore-filling step by two solvents process. The structural and textural properties of the SBA-15 template and α-Fe2O3-2.0 catalyst were characterized by means of X-ray diffraction, transmission electron microscopy and nitrogen adsorption–desorption techniques. The findings indicated that the resulting iron oxides are crystalline and to some extent, have negative replica structures of mesoporous SBA-15 template. The catalytic performance of mesoporous α-Fe2O3 towards thermal decomposition of ammonium perchlorate was evaluated by differential scanning calorimetry technique. The specific heat released from the AP decomposition in the presence of catalyst was improved by increasing the precursor to template weight ratio. Therefore, the specific resulting heat released from the composite of AP and mesoporous α-Fe2O3-2.0 (1110 J/g) was ~3 folds of that for pure AP (423 J/g).