This study is concerned with copolymerization of acrylonitrile(AN) with methyl acrylagte(MA) and itaconic acid(IA) using the sodium sulfite/sodium chlorate initiator in aqueous zinc chloride($ZnCl_{2}$) solution. Since the itaconic acid(IA) comonomer is a potential initiator of cyclization, the introduction of IA comonomer into polyacrylonitrile(PAN) precursor can depress the onset and peak temperatures of the DSC exothermic peak obtained in the course of oxidative heating. With increase in the IA content, the conversion of acrylonitrile(AN) and the rate of polymerization were reduced. The comonomer content, as well as the nature of the comonomer, played a significant role in the stabilization process of the copolymer. The best result was obtained at about 2 mol% of IA.