In this work we have utilized MOF-199 as a well known copper-based metal-organic framework (MOF), to study the thermal behavior of ammonium nitrate (AN). Our results indicate that MOFs improve thermal behavior of AN through their Lewis/Bronsted acid sites as well as their porous structure. Accordingly, MOF-199 (at least 5% by weight) stabilizes phase transition of AN up to 125 degrees C while [Cu-2(bdc)(2)(bpy)] is not a suitable MOF of choice. In addition, DSC studies showed a sharp exothermic peak for AN-MOF-199 composite related to the rapid catalytic combustion of the composite.