Electro-hydro-dynamic atomization,commonly referred to as electrospray,is a versatile technique to produce mono-disperse nano-materials.Numerous strategies have been adopted,ranging from simple evaporation driven crystallization to complex chemical reactions within the uniformly sized droplet micro-reactors,to produce nano-particles and composites of a wide range of materials,and with varied architectures.Ammonium Perchlorate(AP)is the most common oxidizer used in various composite solid rocket propellant formulations.Its size dependent properties such as its thermal behavior,sensitivity,combustion and detonation properties,particularly in the nano-regime,have been of immense interest in the recent past due to its technological implications.However,there are not many methods reported by which pure and mono-disperse AP nano-particles can be prepared.In this paper,we report for the first time the synthesis of pure and ultrafine AP via electrospray technique.Principally,AP dissolved in low boiling point solvent(s)was electrospray-dried to produce monodisperse spherical nano-particles with diameter controllable from few microns to few hundred nanometers.Typically,voltages of 5-8 kV were used to obtain a stable Taylor cone,and a circular electrostatic diffuser was used to aid in faster evaporation of solvent during time of flight.Various parameters affecting the electrospray process and the ensuing AP particles have been systematically studied and related,and their operating windows have been established.Further,thermal studies of the nano-sized AP prepared by this electrospray technique reveal a substantial size effect in terms of its lowered thermal decomposition temperature; over 100 oC as compared to micron-sized AP particles.