Abstract: A process for producing hydrazine containing at least 98 percent by weight of N.sub.2 H.sub.4 which admixes an aqueous solution of hydrazine with an alkali metal hydroxide to form a hydrazine solution having a N.sub.2 H.sub.4 concentration of at least 70 percent by weight. The molar ratio of alkali metal hydroxide to water is less than about 0.5:1. The concentrated hydrazine solution is distilled in a fractional distillation apparatus at an overhead vapor temperature below about 50.degree. C. and at a pressure of less than about 60 mm Hg.

Abstract: Ultrapure or anhydrous hydrazine is produced in a process which comprises distilling aqueous solutions of hydrazine having at least 70 percent by weight of N.sub.2 H.sub.4 at pressures below about 20 millimeters. Aqueous solutions of hydrazine are dehydrated with solid inorganic compounds such as alkali metal hydroxides which are essentially carbon-free. The concentrated hydrazine solution is then distilled at reduced pressures and temperatures which minimize the hazardous conditions present when using processes of the prior art. Monopropellant hydrazine suitable for use in spacecraft engines can be produced having a N.sub.2 H.sub.4 concentration of at least 99.5 percent and less than 5 parts per million of volatile carbonaceous materials.