Abstract: An application of supercritical fluids technology for processing of budesonide-poly (ethylene oxide) solid dispersions was presented. The correlations of the operation parameters in the preparation process were studied. Solid dispersions of budesonide in poly (ethylene oxide) were prepared using a static method for supercritical carbon dioxide and characterized by powder X-ray diffractometry, differential scanning calorimetry, intrinsic dissolution, and in vitro dissolution. It was found that the optimum condition of solid dispersions formation was as follows: temperature, 40 ℃; pressure, 20 MPa; the ratio of budesonide and poly (ethylene oxide), 1∶10. Drug existed in amorphous state in hydrophilic poly (ethylene oxide) carriers and intrinsic solubility and dissolution rates were significantly enhanced. The mechanism of the enhanced dissolution may be attributed to the amorphous character of the budesonide, improvement of the wettability of the hydrophobic budesonide, together with the formation of hydrogen bond of budesonide and hydrophilic poly (ethylene oxide). The supercritical fluids process can be used as an alternative method for preparation of solid dispersions.