AbstractGraft copolymerization of Grewia optiva fiber with acrylic acid (AAc) was carried out by using a Ce(IV) redox initiator under two different conditions, i.e. in air and under the influence of microwave radiation. Different reaction conditions affecting grafting percentage (Pg) for both methods were optimized and compared. Optimized reaction parameters for maximum Pg (7.86%) for graft copolymerization of AAc onto Grewia optiva fiber in air were 90 min reaction time, a temperature of 45° C, 1.82X10-2 mol/L CAN, 2.88X10-1 mol/L nitric acid, and 3.50X10-1 mol/L AAc. However, the maximum Pg (5.56%) for graft copolymerization in the case of MWR were 15 min reaction time, 110 W power, 2.73X10-2 mol/L CAN, 2.88X10-1 mol/L nitric acid, and 2.91X10-1 mol/L AAc. Both raw and graft copolymerized fibers were subjected to the evaluation of some of their properties such as swelling, moisture absorbance, and chemical resistance behavior. The AAc-graft copolymerized Grewia optiva showed 19.23% more swelling when compared with that of raw fiber. Further morphological and structural changes, thermal stability, and the crystallanity of raw, Grewia optiva-g-poly(AAc) in air, and Grewia optiva-g-poly(AAC) under MWR fibers were also studied by SEM, FTIR, TGA, and XRD techniques.