We present a theoretical study on the dissociation reaction of N8 azapantalene to four N2 molecules. The process proceeds via isomerization of N8 azapentalene to N8 azidopentazole, which then dissociates directly into four nitrogen molecules. The calculations have determined the relative energies of the two isomers and the two transition states involved in the dissociation process. The results show azidopentazole to be 13 kcal/mol more stable than azapentalene. The barrier to dissociation into four N2 molecules is computed to be 19 kcal/mol. It is concluded that N8 is not stable enough to be considered as a candidate for a high-energy density material. The calculations have been carried out using multiconfigurational self-consistent field and second-order perturbation theory.