Octaazacubane is a hypothetical explosive allotrope of nitrogen with formula N8, whose molecules have eight atoms arranged into a cube.

It can be regarded as a cubane-type cluster, where all eight corners are nitrogen atoms bonded along the edges.

[2] It is predicted to be a metastable molecule, in which despite the thermodynamic instability caused by bond strain, and the high energy of the N–N single bonds, the molecule remains kinetically stable for reasons of orbital symmetry.

[3] Octaazacubane is predicted to have an energy density (assuming decomposition into N2) of 22.9 MJ/kg,[4] which is over 5 times the standard value of TNT.

It has therefore been proposed (along with other exotic nitrogen allotropes) as an explosive, and as a component of high performance rocket fuel.