The polymerization of styrene using the combined system diphenyl zinc-bis(n-butylcyclopentadienyl) titanium dichloride-methylaluminoxane, Ph2Zn-(n-BuCp)(2)TiCl2-MAO, in toluene at 60 degrees C, produced highly syndiotactic polystyrene, confirming that Ph2Zn-titanocene-MAO are good initiator systems for the stereoregular polymerization of styrene. The syndiotacticity of PS was established by its insolubility in chloroform, benzene or toluene, and after continuous extraction in boiling butanone. DSC analysis showed endotherm signals corresponding to the melting temperature, T-m, of syndiotactic polystyrene.