Using of petro-polymers such as polymethylmethacrylate, polypropylene and polyethylene in the world has been undergoing a critical problem due to significantly decreasing of petroleoum stock as monomer sources. Therefore reducing of the petro-polymer usage should be performed by using natural resources such as modified starches.This study reported addition of an acyl bromide compound to substitute hydroxyl groups on the starch obtains a macro initiator for graft-copolymerizing polymethylmethacrylate (PMMA) onto the functionalized starch as starch-g-PMMA through atomic transfer radical polymerization (ATRP) method. The starch activation through the substitution of the hydroxyl functional group creates ability of the starch to transfer a radical atom onto a petro-monomer such an alkylmethacrylate which furthermore polymerize into starch-g-PMMA at mild condition. This paper reported study of the starch activation describing about screening catalysts and acyl bromide compounds, optimizing process variables such as amount ratio of a selected acyl bromide compound to starch and temperature. The functionalized starchs were analysed by 13-CNMR, FTIR, titration and their morphology was observed by FE-SEM.