Bulk polymerization of vinyl chloride (VC) with Cp*Ti(OPh)(3)/MAO catalyst was investigated. The bulk polymerization of VC with Cp*Ti(OPh)3/MAO catalyst proceeded to give poly(vinyl chloride) (PVC) with high molecular weight in good yields. The M-n of the polymer increased in direct proportion to polymer yields and the line passed through the origin. The M-w/M-n of the polymer decreased with an increase of polymer yield. The GPC elution curves were unimodal and the whole curves shifted clearly to the higher molecular weight as a function of reaction time. This indicates that the control of molecular weight can be achieved in the polymerization of VC with Cp*Ti(OPh)3/MAO catalyst even in bulk. The structure of PVC obtained from the bulk polymerization of VC with Cp*Ti(OPh)3/MAO catalyst consists of a regular structure. The thermal stability of the polymer obtained with Cp*Ti(OPh)/MAO catalyst was higher than that of PVC obtained from radical polymerization and depended on the molecular weight of the polymer. In contrast to that, the initial decomposition temperature of the polymer obtained from a radical polymerization did not depend on the molecular weight. We presumed that the decomposition of the polymer obtained with Cp*Ti(OPh)(3)/MAO catalyst initiated at the chain end. (c) 2008 Elsevier Ltd. All rights reserved.