The graft copolymerization of methyl methacrylate (MMA) onto high a-cellulose was carried out homogeneously in an NN-dimethyl acetamide/ lithium chloride solvent system by using benzoyl peroxide as radical initiator. The rate of grafting was evaluated as a function of concentrations of initiator and monomer, reaction time, and temperature. The grafted products were characterized with the help of infrared spectroscopy, whereas the thermal decomposition of optimum PMMA-grafted high a-cellulose was studied using TGA, DTG, and DTA techniques at two heating rates, 10 and 20degreesC/min, in nitrogen atmosphere in the range of room temperature to 650degreesC. Three major decomposition steps were identified and the relative thermal stabilities of the PMMA-grafted high a-cellulose products were assessed. The kinetic parameters for the three decomposition steps were estimated with the help of two well-known methods. The thermal stability of the grafted products decreased with the increase of graft yield (GY). Crystallinity or peak intensity of wide-angle X-ray diffraction patterns decreased with the increase of GY. (C) 2004 Wiley Periodicals, Inc.