Supercritical antisolvent (SAS) method is an emerging technique for particle processing of high energetic materials. The study investigates the recrystallization of high energy material HMX (octahydro- 1,3,5,7-tetranitro-1,3,5,7-tetrazocine) using SAS method. The effect of pressure, solution flow rate, supercritical antisolvent flow rate and temperature on particle size and morphology of HMX crystals has been studied with acetone as solvent and supercritical carbon dioxide as antisolvent. Stable and desirable ��- polymorphic form of HMX could be obtained under certain process conditions and has been confirmed by FTIR spectroscopy. The experimental results show that ��- polymorph of HMX is of rhombohedral morphology with mean particle size of 13.7 μm, as confirmed by SEM and particle size analyzer respectively.