The cationic polymerization of isobutylene using 2-phenyl-2-propanol (CumOH)/AlCl3OBu2 and H2O/AlCl3OBu2 initiating systems in nonpolar solvents (toluene, n-hexane) at elevated temperatures (-20 to 30 degrees C) is reported. With CumOH/AlCl3OBu2 initiating system, the reaction proceeded by controlled initiation via CumOH, followed by beta-H abstraction and then irreversible termination, thus, affording polymers (M-n = 1000-2000 g mol(-1)) with high content of vinylidene end groups (85-91%), although the monomer conversion was low (<= 35%) and polymers exhibited relatively broad molecular weight distribution (MWD; M-w/M-n = 2.3-3.5). H2O/AlCl3OBu2 initiating system induced chain-transfer dominated cationic polymerization of isobutylene via a selective beta-H abstraction by free base (Bu2O). Under these conditions, polymers with very high content of desired exo-olefin terminal groups (89-94%) in high yield (> 85%) were obtained in 10 min. It was shown that the molecular weight of polyisobutylenes obtained with H2O/AlCl3OBu2 initiating system could be easily controlled in a range 1000-10,000 g mol(-1) by changing the reaction temperature from -40 to 30 degrees C. The MWD was rather broad (M-w/M-n = 2.5-3.5) at low reaction temperatures (from -40 to 10 degrees C), but became narrower (M-w/M-n <= 2.1) at temperatures higher than 10 degrees C. (c) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 50: 750-758, 2012