This study focuses on synthesis of pH-sensitive graft copolymer and its characterizations which can be effectively used for various applications, viz. controlled drug delivery, heavy metal adsorption, etc. Itaconic acid-grafted-guar gum (IA-g-GG) copolymer was prepared by free radical mechanism using ceric ammonium sulfate (CAS) as an initiator. Influence of concentration of CAS, IA, reaction temperature and reaction time on grafting efficiency was investigated. Plausible mechanism for grafting reaction was suggested. The graft copolymer formed was characterized by Fourier transform infrared (FTIR), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Swelling studies of the graft hydrogel was carried out in both acidic (pH 1.2) and basic (pH 7.4) media.