Syndiotactic and isotactic polypropylene were produced using the metallocene compounds Ph2C(Flu)(Cp)ZrCl2 and SiMe2(2-Me,4-Ph-Ind)(2)ZrCl2 in homogeneous system and supported on silica/MAO. These catalysts were evaluated either isolated or as a binary system. In the latter case, the iso- and syndiospecific metallocene complexes were immobilized together during the preparation of the supported catalyst. In a further experimental set, the syndio-and isospecific isolated heterogeneous catalysts were mixed at the moment of propylene polymerization. The polypropylenes obtained were evaluated using differential scanning calorimetry. The catalytic activities were also investigated. At all the studied polymerization temperatures, the results showed that the binary catalyst produced polypropylenes with lower melting temperatures in comparison with those obtained when the mixture of isolated supported syndio- and isospecific catalysts was employed. Moreover, the activation energies for the polymerization of all catalysts systems were calculated, resulting in a lower value for the binary system when compared to that employing the catalyst mixture and to both the isolated supported metallocene catalysts.(c) 2005 Wiley Periodicals, Inc.