Commercial zeolite acid mordenite was thermally treated for use as a support for bis(n-butyl-cyclopentadienyl)zirconium dichloride [(n-BuCp)(2)ZrCl2] for the further evaluation of ethylene/1-hexene copolymerization. The polymerization time, temperature, and solvent, as well as the addition of tri(isobutyl)aluminum in the hexane medium, were evaluated. The catalytic activity and 1-hexene content in the copolymer synthesized with the supported system were very near those obtained with the homogeneous precursor. A comonomer effect was observed for both systems. The polymerization rate profiles were obtained for ethylene polymerization, and the activation energy and monomer reactivity were calculated. (C) 2004 Wiley Periodicals, Inc.