1,4-bis-[1-methyltetrazol-5-yl]-1,4-dimethyl-2-tetrazene a formal hexamer of diazomethane can be viewed as a new stable high energy density material (HEDM) with the properties necessary for a potential green chemistry gas generator. The physical properties of the new tetrazene were determined by drop hammer and combined IR and MS pyrolysis experiments. The structure and bonding are discussed on the basis of X-ray, MO and NBO analysis.