Graft-copolymerization of acrylamide onto starch initiated by the Ce4+-S2O2-8binary system has been studied.It has been found that Ce3+ can be reoxidized to Ce4+ by in silo to achieve a Ce4+→ Ce3+→Ce4+ rreaction cycle that leads to cyclic use of Ce4+ ions and thus significant decrease in the initial concentration of ceric[Ce4+]comparing to the use of ceric initiator alone.Grafting ratios of graft-copolymerization by the Ce4+—S2O2-8binary system have been compared with those seing ceric or persalfate initator respectively. Structures of the grafted copolymers have been determined

and their molecular weights have been calculated.