Homogeneous ethylene and propylene polymerisation with new mixed-ligand chloroalcoholate of hafnocene was investigated. The catalytic activity of the complex was studied in comparison with Cp2HfCl2 pre-treated with 2-methyladamantan-2-ol in different molar ratios. The addition of the bridged alicyclic alcohol to the metallocene does not deactivate the catalytic system, but results similar to those obtained with the corresponding mixed-ligand hafnocenes were obtained. The voluminous alcoholato-moiety makes part of the [MAdO-MAO](-) counter-ion where it promotes regioerrors in the growing polymer chain. The X-ray structure of new complex was determined. (c) 2005 Elsevier Ltd. All rights reserved.