The particle size of the pharmaceutical substances is important for their bioavailability (the percentage of the drug absorbed compared to its initial dosage). The absorption rate can be increased by reducing particle size of the drug particles. This study was conducted to investigate the effects of the extraction pressure (140-220 bar), extraction temperature (308-338 K), nozzle length (2-15 mm), effective nozzle diameter (450-1700 mu m), and collection distance (1-10 cm) on the size and morphology of the precipitated ketoprofen particles. The characterization (size and morphology) of the particles was investigated using scanning electron microscopy (SEM). The average particle size of the original material was 115.42 mu m, while the average particle size of the micronized particles is between 0.35 and 7.03 mu m near to quisi-spherical, needle and irregular shape depending upon the experimental conditions. (C) 2010 Elsevier Ltd. All rights reserved.