Propylene polymerization was carried out using an ansa-zirconoeene pyrrolidide based catalytic system of racemic ethylene-1,2-bis(1-indenyl)zirconium dipyrrolidide [rac-(EBI)Zr(NC4H8)(2) or (rac-1)] and methylaluminoxane (MAO) or a noncoordinating anion. In situ generation of cationic alkylzirconium species was also investigated by NMR-scale reactions of rac-1 and MAO, and rac-1, AlMe3, and [Ph3C] [B(C6F5)(4)]. In the NMR-scale reaction using CD2Cl2 as a solvent, a small amount of MAO ([Al]/[Zr] = 30) was enough to completely activate rac-1 to give cationic methylzirconium cations that can polymerize propylene. The resulting isotactic polypropylene (IPP) isolated in this reaction showed a meso pentad value of 91.3%. In a similar NMR-scale reaction rac-1 was stoichiometrically methylated by AlMe3 to give rac-(EBI)ZrMe2, and the introduction of [Ph3C] [B(C6F5)(4)] into the reaction mixture containing rac-(EBI)ZrMe2 led to in situ generation of cationic [rac-(EBI)Zr(mu-AlMe)(2)AlMe2](+) species that can polymerize propylene to give iPP showing a meso pentad value of 94.7%. The catalyst system rac-1/MAO exhibited an increase of activity as the [AI]/[Zr] ratio increased within an experimental range ([Al]/[Zr] = 930-6511). The meso pentad values of the resulting iPPs were in the range of 83.2-87.5%. The catalytic activity showed a maximum (<(R-p)over bar>, = 6.66 x 10(6) g PP/mol Zr h atm) when [Zr] was 84.9 x 10(-6) mol/L in the propylene polymerization according to the concentration of catalyst. MAO-free polymerization of propylene was performed by a rac-1/AlR3/noncoordinating anion catalytic system. The efficiency of AIR, was decreased in the order of AlMe3 (<(R-p)over bar> = 13.0 x 10(6) g PP/mol Zr h atm) > Al(i-Bu)(3) (8.9 x 10(6)) > AlPr3 (8.8 x 10(6)) > Al(i-Bu)(2)H (8.4 x 10(6)) > AlEt3 (8.4 x 10(6)). The performance of the noncoordinating anion as a cocatalyst was on the order of [HNMePh2][B(C6F5)(4)] (<(R-p)over bar> = 13.0 x 10(6) g PP/mol Zr h atm) > [HNMe2Ph][B(C6F5)(4)] (10.8 x 10(6)) > [Ph3C][B(C6F5)(4)] (8.4 x 10(6)) > [HNEt2Ph][B(C6F5)(4)] (7.8 x 10(6)). The properties of iPP were characterized by C-13-NMR, FTIR, DSC, GPC, and viscometry.