The paper deals with basic problems of the study of the thermal reactivity of individual energetic materials with special attention on the compatibility of results obtained using different methods. It is shown that the activation energies for thermal decomposition of these materials, obtained under comparable conditions, correlate with the respective detonation heats through a modified Evans-Polanyi-Semenov equation. These correlation relationships apply within groups of molecules with closely related structures and underline the importance of the bond that is primarily split in the molecule for the detonation of a given material. They also indicate that the primary fragmentation processes during low-temperature thermal decomposition are the same as those controlling the detonation reaction. It is shown that the correlation relationships found are also valid in the case of electric spark initiation.