synopsisPolymerization of vinyl chloride by the ternary catalyst system of VOCbALR,Cb-ncomplexing agent waa investigated. It was suggwted that the formation of a polar complex (or chargedmnsfer complex) between AlRnCb-n and the complexing agent participated in the polymerization of vinyl chloride. In the copolymerization of vinyl chloride with propylene with the present catalyst system, it waa more diflicult to incorporate the propylene unit in the copolymer than with a typical radical catalyst.