The polymerization of acrylonitrile initiated by potassium bromate coupled with thioacetamide was investigated in aqueous solution under nitrogen atmosphere. The effect of monomer, initiator, activator, and acid concentration on the rate of polymerization as well as on maximum conversion was evaluated. The rate of polymerization was found to increase up to 1.25 × 10−3Mof initiator concentration and thereafter it decreased. The rate of polymerization also increased with the monomer and activator concentration up to 1.5078 and 4.0 × 10−3M, respectively, after which the rate fell. The effect of acid concentration, temperature, and solvents on rate of polymerization has been studied and a suitable kinetic scheme has been pictured.