Chain transfer with adsorbed aluminium alkyl has been investigated for the system VCI 3/AIR 3/4-methylpentene-1, where adsorption of the metal alkyl onto the catalyst surface is described by a Langmuir type adsorption isotherm. Rate constants for chain transfer with metal alkyl and equilibrium constants for adsorption of a series of aluminium alkyls and 4-methylpentene-1 onto the transition metal halide surface have been determined. The activation energy for the chain transfer process with tri-isobutylaluminium has also been evaluated. The number of active centres is found to be reduced at low monomer concentrations probably because of slow initiation by monomer. Quantitative verification of a previously presented kinetic scheme has been effected.