The catalytic properties of ((RPh)-Ph-X)(2)C(Cp)(Flu)MCl2 complexes (R-X = Cl, F or CF3; M = Zr or Hf) in propylene polymerization were studied. The results showed dependences of stereospecificity and polymerization activity on the substituent on phenyl group. When R-X is CF3, the activity is 1.38 times of that of the complex with no substituent at 1 atm propylene pressure and is extremely high at 3.0 MPa propylene pressure. The CF3 group increased the regioirregular insertion during polymerization to produce partially crystalline s-PP. When R-X is halogen, the obtained polymer has higher melting point than that obtained from the complex with no substituent. (C) 2004 Elsevier B.V. All rights reserved.