The polymerization of styrene using combined systems of diphenylzinc-biscyclopentadienyltitanium dichloride-methylaluminoxane, Ph2Zn-Cp2TiCl2-MAO, in toluene at 60 degrees C produced highly syndiotactic polystyrene. The syndiotacticity was established first by polymer insolubility in chloroform benzene or toluene, and also by continuous extraction in boiling butanone. DSC analysis confirmed this finding and showed signals corresponding to the melting temperature, T-m, of syndiotactic polystyrene.