Ammonium persulphate (APS) has been used as efficient initiator for graft copolymerization of the aniline (ANI) onto chitosan at 25±0.1°C. Graft copolymerization of ANI onto chitosan has taken place through the cation radical initiation process. The grafting parameters have been evaluated by varying concentration of ANI, APS and chitosan. The effects of concentration of APS, ANI, chitosan and reaction time on graft copolymerization were studied by determining the grafting percentage (%G), grafting efficiency (%E) and percentage add-on. It was observed that bout rate of homopolymerization (Rh) and rate of graft coplymerization (Rg) increased with the increase in concentration of each component. On the basis of the experimental observations, initiating steps have been proposed and a suitable rate expression for graft copolymerization has been derived. Electrical conductivity of grafted polyaniline (PANI) onto chitosan (Chit-g-PANI, chitaline) was measured by the four probe method.