A new method for the preparation of microporous particles of isotactic polypropylene (IPP) using thermally induced phase separation (TIPS) was developed in this study, in which chloroform was used as a diluent and Span80 was used as a pore-forming agent. The morphology and properties of the microporous IPP particles thus produced were characterized with scanning electron microscopy, mercury intrusion porosimetry, and differential scanning calorimetry, and they were compared with IPP particles produced by a cryogenic pulverization method. The results showed that IPP particles with a fully developed microporous structure, an average particle size between 50 and 120 mu m, and a specific area of about 5.19 m(2)/g can be obtained via the TIPS method under definite conditions. The influence of some factors on the size and porosity of IPP particles is discussed. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 3050-3057, 2009