Abstract: A phase-stable, oxidizer-grade zinc diammine complex stabilized ammonium nitrate that retains its phase-stability, has a minimum hygroscopicity and cure interference, is prepared by dissolving an anhydrous zinc diammine complex, which may be either the sulfate, perchlorate or nitrate, in dry molten ammonium nitrate. The complex is best prepared in a separate step by melting a 3/1 molar mixture of ammonium nitrate with zinc oxide which produces the zinc diammine dinitrate complex contaminated with the water of the reaction. The melt is dried by driving off the water. First by simple boiling, and the final traces by means of purging with dry air or nitrogen gas. The ammonia lost in this drying operation is exactly replenished by purging with anhydrous ammonia gas. The sulfate complex is obtained by co-dissolving an essentially stoichiometric quantity of ammonium sulfate in either the melt of the complex or the bulk of the molten ammonium nitrate.