The graft copolymerization of acrylonitrile (AN) onto natural wool fibers initiated by KMnO4 and oxalic acid combined redox initiator system in limited aqueous medium was carried out in heterogeneous media. Moreover, modification of the grafted wool fibers was done by changing the nitrile group (-CN) into cyano-acetic acid alpha-amino-acrylic-hydrazide through the reaction with hydrazine hydrate followed by ethylcyanoacetate which eventually produce wool-grafted-poly(cyano-acetic acid alpha-amino-acrylic-hydrazide) (wool-g-PCAH) chelating fibers. The application of the modified fibers for metal ion uptake was studied using Hg2+, Cu2+ and Co2+. The modified chelating fibers were characterized using FTIR spectroscopy. SEM and X-ray diffraction. (c) 2010 Elsevier B.V. All rights reserved.