The homopolymerization of 5-alkyl-2-norbornenes and their copolymerization with norbornene have been successfully carried out employing Pd(acac)(2)/PPh3/BF3OEt2 catalyst system. The activity of the catalyst system is comparable to that of most active late-transition metal catalysts described in the literature. The molecular weight distributions of homo- and copolymers indicate a single-site, highly homogeneous character of the active catalyst species. The incorporation of flexible alkyl groups onto the main chain of norbornene as well as copolymerization of 5-alkyl-2-norbornenes with norbornene represent useful methods for lowering the glass transition temperature (T-g), i.e. improving the processability. The simplicity of catalytic system composition might be of industrial importance. © 2005 Elsevier Ltd. All rights reserved.