A study on the graft copolymerization of methyl methacrylate onto defatted jute fibers by using potassium permanganate as initiator has been made. To determine the optimum conditions for grafting, the effects of permanganate, monomer, acid, alkali treatment, time, and temperature on percentage of grafting have been studied. Kinetic studies showed that the overall reaction obeyed second order mechanism. The activation energy of the reaction has been found to be 4.34 kcal/mol. A suitable mechanism for the grafting process has been proposed. The grafted fibers have been characterized by thermogravimetric analysis (TGA, DTG, and DTA). It has been found that chemical modification of jute fiber by grafting process using permanganate as the initiator does not improve the tensile properties of the fibers.