Graft copolymers of potato starch with acrylamide, acrylamide, and acrylic acid or N-vinylformamide in the presence of 1-16 wt % montmorillonite were manufactured via reactive extrusion. XRD and TEM measurements exhibited intercalated structure of clay dispersion (d001 distance up to 2.3 nm). The influence of graft polymer(s) system and montmorillonite content on thermal properties, water sorption as well as polyvalent metal cation (Cd2+ and Fe3+) sorption of obtained starch graft copolymers has been determined. (C) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 127: 2847-2854, 2013