AbstractA kinetic study has been made of the polymerization of methyl methacrylate (MMA) initiated by a charge‐transfer complex of poly‐2‐vinylpyridine (electron donor) and liquid sulfur dioxide (acceptor) in the presence of carbon tetrachloride. It is concluded that the polymerization proceeds through free‐radical intermediates, as with the pyridine‐liquid sulfur dioxide complex system. The association constantsKof acceptor and polymer electron donors which range widely in their molecular weight were determined spectrophotometrically, and it has been found that bothKand overall rate of polymerizationRpof MMA decrease with increasing molecular weight of polymer donor; contrary to this, molecular weight of PMMA formed increases with increasing molecular weight of the polymer donor. Other kinetic behaviors was essentially the same as in the pyridine–liquid sulfur dioxide system, i.e.,Rpis proportional to the square root of the concentration of the complex and to the 3/2‐order of the monomer concentration;Rpis clearly sensitive to the carbon tetrachloride concentration at low concentration of carbon tetrachloride, but for a higher concentration it is practically independent of the carbon tetrachloride concentration. It has been deduced from a kinetic mechanism for the initiation that a primary radical may be produced from the reduction of carbon tetrachloride by an associated complex consisting of liquid sulfur dioxide–polymer donor