The heats of formation of N2H, diazene (cis- and trans-N2H2), N2H3, and hydrazine (N2H4), as well as their protonated species (diazenium, N2H3+, and hydrazinium, N2H5+), have been calculated by using high level electronic structure theory. Energies were calculated by using coupled cluster theory with a perturbative treatment of the triple excitations (CCSD(T)) and employing augmented correlation consistent basis sets (aug-cc-pVnZ) up to quintuple-zeta, to perform a complete basis set extrapolation for the energy. Geometries were optimized at the CCSD(T) level with the aug-cc-pVDZ and aug-cc-pVTZ basis sets. Core-valence and scalar relativistic corrections were included, as well as scaled zero point energies. We find the following heats of formation (kcal/ mol) at 0 (298) K: Delta H-f(N2H) = 60.8 (60.1); Delta H-f(cis-N2H2) = 54.9 (53.2); Delta H-f(trans-N2H2) = 49.9 (48.1) versus >= 48.8 +/- 0.5 (exptl, 0 K); Delta H-f(N2H4) = 26.6 (23.1) versus 22.8 +/- 0.2 (exptl, 298 K); Delta H-f(N2H3) = 56.2 (53.6); Delta H-f(N2H3+) = 231.6 (228.9); and Delta Hf(N2H5+) = 187.1 (182.7). In addition, we calculated the heats of formation of CH3NH2, CH3NNH, and CH3HNNHCH3 by using isodesmic reactions and at the G3(MP2) level. The calculated results for the hydrogenation reaction RNNR + H-2 -> RHNNHR show that substitution of an organic substituent for H improved the energetics, suggesting that these types of compounds may be possible to use in a chemical hydrogen storage system.