5-Amino-1-benzyloxytetrazole was aminated with O-tosylhydroxylamine. The diaminobenzyloxytetrazolium intermediate was debenzylated to yield the highly energetic 1,5-diaminotetrazole-4N-oxide (SYX-9). The molecule underwent both chemical and energetic characterization, including ¹⁵N NMR spectroscopy and single-crystal X-ray crystallography, which reported a 1.820 g cm⁻³ ambient temperature density. Theoretical energetic performances were determined by a combined experimental–computational method using calculated heats of formation and experimental room temperature densities. SYX-9 was calculated to have an exciting detonation velocity of 10 000 m s⁻¹, making this energetic tetrazole molecule one of the few energetic materials reaching this high performance milestone. This material was found to be very sensitive to mechanical and thermal stimuli.