Thermal reactivity of eleven nitramines has been examined by means of non-isothermal differential thermal analysis, and the data were analyzed according to the Kissinger method. The reactivity was expressed as the EaR−1 slopes of the Kissinger relationship. Electronic charges, qN, at nitrogen atoms of the nitramine molecules were calculated by means of ab initio DFT B3LYP/6-31G** method. The relationships were confirmed between the slopes EaR−1 and the q values for the nitro groups that are primarily split off. Conclusions are made in relation to the mechanism of initiation of polynitro compounds in general.