Telechelic polyisobutylene with chlorine end-groups was made by cationic polymerization of isobutylene in methylene chloride with difunctional initiators (2,5-dimethoxy-2,5-dimethylhexane and 2,5-diacetyl-2,5-dimethylhexane). The structure of these initiators resembles that of polyisobutylene. BCl3 and TiCl4 were used as catalysts. The molecular weight of these telechelics was varied between 600 and 3500 g mol-1, with a molecular-weight distribution ranging from 1.3 to 2.1. The materials were characterized by high-performance liquid chromatography, nuclear magnetic resonance and infra-red spectroscopy.