Cyclopentadienyl-titanium complexes containing -OC6H4X ligands (X = NO2, Cl, H, C(CH3)(3), OCH3) were synthesized. The "X" substituents at the phenoxy ligands have different electron donor properties, which are described by Hammett's factors. Mixtures of CpTiCl2(OC6H4X-p) and MAO were investigated by polarography. The amount of Ti(III) ions have been noticed. EPR spectra were recorded for mixtures of CpTiCl2(OC6H4X-p) with MAO and styrene. The shape and the parameters of the EPR spectra were found to be related to the nature of -OC6H4X-p ligands. (C) 2002 Elsevier Science B,V. All rights reserved.