The aim of this study was to determine the effect of chemical modification on selected physicochemical properties of potato starch powder. Esterification with acetic anhydride and adipic anhydride (E 1422 starch) caused the most pronounced changes in physicochemical parameters compared with native potato starch powder. In native and E 1422 starches, mean granule diameter changed from 23.1 to 25.4 mu m, shape factor from 1.47 to 1.33, specific surface from 0.2115 to 0.1695 m(2) g(-1), porosity from 41.31% to 45.29%, water absorption increased up to 50%, and flow behavior changed from easy to cohesive. A microscopic analysis confirmed also the differences in the surface morphology showing the most rough surface of E 1422 starch. Despite broad variations in the diameter of individual starch granules, it was found that differently sized ridges and valleys on granule surface reflect porosity and water sorption values of the examined starches. (C) 2011 Elsevier Ltd. All rights reserved.