Graft copolymerization of acrylonitrile (AN) onto chemically modified pineapple leaf fiber (PALF) was studied using Ce(IV) and N-acetylglycine (NAG) combination as initiator in the temperature range 40-60 degrees C. The effects of concentration of monomer, Ce(IV), and NAG on graft yield have been studied. Besides the effects of time, temperature, acid, amount of PALF, some inorganic salts and organic solvents on graft yield have been investigated. FTIR and scanning electron microscopy of PALF and grafted PALF have been studied. Grafting has improved the thermal stability of PALF.