Propene polymerization was carried out by Cp*Ti(CH2Ph)(3), [t-BuNSiMe2(C5Me4)]TiMe2 and [t-BuNSiMe(2)Flu]TiMe2 combined with dried Or SiO2-supported methylaluminoxane (MAO). The dried MAO system generally showed higher activity and gave higher molecular weight polypropenes than the SiO2-supported MAO system. The decrease in the activity by changing the cocatalyst from dried MAO to SiO2-supported MAO was, however, more significant in the cases of [t-BuNSiMe2(C5Me4)]TiMe2 and [t-BuNSiMe(2)Flu]TiMe2. The molecular weight distribution of the produced polymers indicated that uniform active species were formed from Cp*Ti(CH2Ph)(3) regardless of the cocatalyst employed while the active species derived from [t-BuNSiMe2(C5Me4)]TiMe2 and [t-BuNSiMe(2)Flu]TiMe2 combined with SiO2-supported MAO were inhomogencous. The microstructure of the produced polymers were independent of the cocatalyst used, and [t-BuNSiMe(2)Flu]TiMe2 catalysts produced syndiotactic polypropenes with less regioirregular structure. The Cp*Ti(CH2Ph)(3)/SiO2-supported MAO system showed a steady polymerization rate with frequent chain transfer at 0degreesC while the [t-BuNSiMe2(C5Me4)]TiMe2/SiO2-supported MAO system produced the polypropenes with long chain lifetime accompanied by slow deactivation at 0degreesC.