The development of new high-performance propellant combinations requires the establishment of safety and handling characteristics and thermodynamic decomposition and explosive properties. This paper addresses the early development phases of a new composite solid propellant based on HNF as oxidizer and GAP as an energetic binder. A pilot plant for the production of HNF has been consented and many of the properties of HNF and HNF/AYGAP propellants have been established. Initial development tests show that HNF looks suitable as a propellant oxidizer, while initial tests with HNF/AVGAP confirm the expected increase in performance over existing composite propellants. Impact and friction sensitivity have been determined for HNF and HNF based propellants. Areas which require additional investigation are also addressed. © 1995 by ESAESTEC. Published by the American Institute of Aeronautics and Astronautics, Inc.