Dissociation pathways of N-9 (C-2 nu) and N-9(+) (C-2 nu) clusters have been investigated by ab initio molecular orbital theory and density functional theory methods. The reactants and products involved were optimized at the HF/6-31G*, B3PW91/6-31C*, B3LYP/6-31G*, and MP2/6-31G* levels of theory. Transition states of decomposition processes were found and characterized on the HF/6-31G*, B3PW91/6-31G*, and B3LYP/6-31G* potential energy surfaces (PES), At the above levels, the barrier heights of the process N-9 --> N-6 + N-3, with zero point energy corrections, are predicted to be 15.3, 31.8, and 32.9 kcal/mol. Similarly, those of the second step N-6 --> 3N(2) are 8.2, 16.3, and 14.4 kcal/mol. The barrier height of N-9(+) --> N-7(+) + N-2 is 2.1 kcal/mol, and that of second step N-7(+) --> N-2 + N-5(+) is 4.3 kcal/mol at the B3LYP/6-311+G*//B3LYP/6-31G* level. The potential applications of N-9 and N-9(+) as high-energy density materials were examined.