The measurement of the heat of explosion Qex a method to determine the energy content of an energetic material by combustion in a calorimeter bomb was performed for six linear dinitramines (DNDA5, DNDA6, DNDA7, EDNA, M-EDNA, and DM-EDNA), three dinitramines with azido groups (DN3, AZD6, and BAED) and six nitratoethylnitramines (DINA, Me-NENA, Et-NENA, Bu-NENA, BNE-MEDINA, and BNE-EDNA). It was observed that for some substances the determination, based on the combustion of mixtures with nitrocellulose, did not result in constant Qex values, which questioned the general application of the method. This non-linear behavior induced a detailed investigation in order to explain this phenomenon. Constant calculated Qex values lying over 4000 J g-1 with a small deviation were obtained for compounds with an oxygen balance above -60?%, whereas in the range of -60?% to -70?% the Qex values between 3400 and 3700 J g-1 already presented pronounced deviations. However, for compounds with an oxygen balance below -70?%, the calculated Qex value increased strongly with rising percentage of the compound in analyzed mixtures with NC. A reliable value cannot be given in this case. This behavior is explained by different decomposition reactions of the compound, depending also on the pressure and temperature dependent water gas equilibrium and the Boudouard equilibrium. It should be clarified by further investigations and comparison with thermodynamic calculations. Neither the type of energetic groups as NNO2, ONO2, or N3 nor the nitrogen content or the type of energetic additive (RDX or NC) in the analyzed mixtures have any decisive influence on the Qex values.