The grafting of 4-vinyl pyridine (4-VP) onto konjac glucomannan (KGM) by ammonium persulfate (APS) as the initiator was studied in an acid aqueous solution under an inert atmosphere. The grafting ratio (G%) and grafting efficiency (E%) were evaluated comparatively. The dependence of these parameters on the initiator concentration, sulfuric acid concentration, ratio of monomer to KGM, temperature, and reaction time was also investigated. Under conditions of [KGM] = 1.00 g/L, [APS] = 1.00 x 10(-2) mol/L, [4-VP] = 9.32 x 10(-2) mol/L, [H+] = 5.00 x 10(-2) mol/L, temperature = 35 degrees C, and time = 120 min, the optimum G% and E%, were 307.27 and 52.75%, respectively. The proof of grafting was obtained from thermogravimetric analysis and infrared spectra. Preliminary research of the graft's adsorption capacity for heavy-metal ions [Cr(VI), Cu(II), Pb(II), and Cd(II)] was done. (C) 2009 Wiley Periodicals, Inc. J Appl polym Sci 113: 2339-2345, 2009