Combination of diphenylzinc, Ph2Zn, cyclopentadienyl titanium trichloride, CpTiCl3, and methylaluminoxane, MAO, were used to initiate styrene, S, polymerization and its copolymerization with 1-hexadecene, 1-C16H32, and with p-tert-butylstyrene, p-(BuS)-S-t. For homopolymerization an almost pure syndiotatic polystyrene, s-PS, was obtained when using Ph2Zn-CpTiCl3-MAO combination, while other combinations of these components produced atactic polystyrene, a-PS, or almost no polymer at all. CpTiCl3-MAO and Ph2Zn-CpTiCl3-MAO were effective initiator systems for S/1-C16H32 and for S/p-(BuS)-S-t copolymerization. S/1-C16H32 copolymers showed crystalline melting temperature at range 235 - 255 degrees C while S/p-(BuS)-S-t copolymers did not show any melting temperature signal at DSC, but behave as stereoregular polymer.