Unreported graft copolymer of 2-acrylamido-2-methyl-1propanesulphonic acid (AMPS) with sodium carboxymethylellulose (Na-CMC) was synthesized and reaction conditions were optimized using a bromate/thiourea redox pair under an inert atmosphere at 40 degrees C. Grafting ratio, add on, and conversion increase as the concentration of thiourea and [H+] increases up to 3.6 X 10(-3) and 0.6 X 10(-2) mol dm(-3), respectively, while on increasing the concentration of bromate ion and Na-CMC, grafting ratio, add on, and conversion decrease. The samples of Na-CMC and grafted Na-CMC with AMPS were subjected to thermogravimetric analysis, with the objective of studying the effect of grafting of AMPS on the thermal stability of graft copolymer. The graft copolymer was found to be more thermally stable than pure Na-CMC. Comparing the IR spectra of pure with grafted Na-CMC confirm the evidence of grafting. (c) 2005 Wiley Periodicals, Inc.