In order to study the graft modification of chitosan derivatives, hydroxypropyl chitosan (HPCTS) was prepared and characterized by FTIR, (1) H NW and elemental analysis. Methylacrylic acid (MAA) was grafted onto HPCTS in an aqueous solution using ammonium persulfate (APS) as an initiator. Evidence of grafting was obtained by comparison of FTIR spectra of HPCTS and the grafted copolymer as well as solubility characteristics of the products. Variations of grafting percentage and grafting efficiency with reaction time, temperature, concentration of initiator and monomer bad been investigated.