Energies of combustion and specific heat capacities of diaminofurazan(DAF), dinitrofurazan(DNF) and diaminoazofurazan(DAAzF) were determined. Energies of combustion for the three compounds are (-13043±119), (-6863±37) J·g^-1 and (-12661±54) J·g^-1, respectively. The corresponding standard molar enthalpies of formation (Δ_fH_m^Θ) were obtained with the different combustion products. The values of specific heat capacities for the three compounds are (140.8±0.1), (236.8±0.2), (216.9±0.2) J·mol^-1·K^-1, respectively. Energy of combustion tends to rise with the decrease of oxygen content in molecule (DAF>DAAzF>DNF). Amino group contributes to increase energy of combustion, but nitro group has the opposite effect. As for the specific heat capacity, the change rule is opposite to energy of combustion.