The microparticles of 2-hydroxypropyl-${eta}$-cyclodextrin (HP-${eta}$-CD) were prepared using aerosol solvent extraction system (ASES) by employing supercritical carbon dioxide as an antisolvent, The effects of various process parameters such as temperature, pressure, solution concentration and solution flow rate on the formation of HP-${eta}$-CD microparticles were investigated. The HP-${eta}$-CD microparticles prepared by the ASES process were observed to consist of agglomerates of nano-sized (50-200 nm) particles. When an aqueous solution of ethanol was used as a solvent for HP-${eta}$-CD, the HP-${eta}$-CD particles were found to be spherical in shape and to become larger as the water content increased. It was confirmed that the micronization of HP-${eta}$-CD using the ASES process could enhance the inclusion efficiency of ibuprofen/HP-${eta}$-CD complexes significantly.