The polymerization of methyl methacrylate monomer initiated by L-methionine-Ce(IV) sulfate redox system in an acid-aqueous medium was investigated. Partially cross-linked methyl methacrylate polymers with limited solubility in known solvents were obtained. The dependence of polymerization yields on the mole ratio Of L-methionine to cerium(IV) sulfate and methyl methacrylate monomer to cerium(IV) sulfate (n(Ce(IV)) = n(Meth)), polymerization time, acid concentration, temperature, and amount of solvent (acetone and methanol) was investigated. The results of infrared, thermal gravimetric analysis, differantial scanning calorimetry measurements to indicate the thermal oxidative properties of obtained polymers also are given. The possible mechanism for the polymerization reaction is discussed.