Acrylonitrile was grafted on to tamarind seed gum using persulfate/ascorbic acid redox initiator and a representative sample of the graft copolymer (Tm-g-PAN) was characterized using infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Grafting conditions were optimized where %G and %E were found to increase with the increase in the concentration of the monomer; initiator, and the reaction temperature, whereas increase in gum concentration decreased the %G in the concentration range of 4-12 g/L, The maximum % grafting (%G) and % efficiency (%E) achieved were 305 and 75%, respectively. Water/saline retention, gel forming ability, and the shelf life of the grafted gum solutions were also studied to explore the possibility of its commercial utilization. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 539-544, 2009