Half-sandwiched titanocene trichloride (Cp'TiCl3; Cp'= cyclopentadienyl, Cp; pentamethylcyclopentadienyl, Cp*; indenyl, Ind) combined with an alkylaluminum (triisobutylaluminum, diisobutylaluminum hydride, or trioctylaluminum)/Ph3CB(C6F5)(4) cocatalyst system has been examined for polymerization of styrene. Syndiospecific polymerization of styrene proceeded under limited polymerization conditions. The maximum productivity of syndiotactic polystyrene was attained under the following conditions: Al/Ti molar ratio = 20 (mol/mol), polymerization temperature = 40-50 degrees C. The nature of alkylaluminum compounds and the ligand structure of the catalysts affected the range of the polymerization temperature in which proceeds the syndiospecific polymerization of styrene. (c) 2006 Elsevier B.V. All rights reserved.