Monocyclopentadienyltitanium trichloride (CpTiCl3) was directly immobilized on silica surface. The resulting CpTiCl3/SiO2-MAO was investigated in view of its suitability for syndiospecific polymerization of styrene using ESR spectroscopy. Polymerization results show that both the syndiotacticity and the activity decrease upon immobilization. A possible explanation is that the active sites may become aspecific lifter immobilization and part of the immobilized active sites can be leached into the solution in the presence of MAO.