Nanoscale composites of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and polymeric binders were produced by co-precipitation using rapid expansion of supercritical solutions (RESS). The binders used in this study are poly (vinylidene fluoride-co-hexafluoropropylene) (VDF-HFP22) and polystyrene (PS). The RDX/VDF-HFP22 and RDX/PS co-precipitated nanoparticles were characterized by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The average size of produced nanoparticles is ca. 100 nm. TEM analysis of RDX/PS nanocomposite shows a core-shell structure with RDX as the core material and the shell consisting of the polymeric binder. X-ray Powder Diffraction (XRPD) analysis indicates polycrystalline structure of RDX in the product with a crystallite size of 42 nm. The content of RDX in the composite particles is in the range of 70-73% by mass as determined by Gas Chromatography Mass Spectroscopy (GCMS) and by XRPD.