Polyethylene glycol (PEG) is a polymer with many potential applications in pharmaceutical industry; but, it is difficult to process, since it is thermosensitive and tends to produce irregular and aggregated particles. In this work, micronization of PEG6000 and PEG10000 is proposed using Supercritical Assisted Atomization process operating in the new arrangement working at reduced pressure, specifically developed to process thermosensitive compounds. This process improvement allows to apply precipitation temperatures as low as 5 degrees C. When PEG6000 was processed, through the reduction of the precipitation temperature down to 5 degrees C, particles tended to collapse: but, when PEG10000 was processed at the same operating conditions, spherical not aggregated microparticles were obtained with mean diameters ranging between 2 and 3.3 mu m and characterized by sharp particle size distribution. X-ray powder diffraction analysis showed that SAA processed PEG had the same crystalline structure of the unprocessed material. (c) 2012 Published by Elsevier B.V.