Tamarind kernel powder (TKP), a natural xyloglucan polysaccharide is derived from the seeds of Tamarindus indica Linn., a common and most important tree of India and South East Asia. TKP is used in cotton sizing, as a wet-end additive in the paper industry, as a thickening, stabilizing, and gelling agent in the food industry. Chemical modification of TKP through grafting has received considerable attention to impart new functional groups for different applications. Keeping this in view, graft copolymerization of acrylamide (AA) onto TKP was carried out in an aqueous medium using a ceric ammonium nitrate (CAN)-nitric acid initiation system. The reaction conditions were optimized for grafting with respect to the effect of the concentrations of CAN, nitric acid, TKP, AA, time, and reaction temperature. The maximum percentage grafting (%G) and percentage grafting efficiency (%GE) were found to be 231.45 and 93.66%, respectively. (C) 2008 Wiley Periodicals, Inc.