During the last decade there has been increased interest in the development of homogeneous catalytic systems to promote homo- or copolymerization reactions of unsaturated hydrocarbons. This review is focused on systems based on palladium complexes with nitrogen-donor ligands and on their application as catalysts (or precatalysts) for co- and terpolymerization of carbon monoxide and olefins. Detailed catalytic performance is reported (productivity, molecular weight values and stereoregularity of the copolymers) allowing comparison between different systems. Particular attention will be addressed to the relationship between catalyst structure and structural features of the polymers synthesized. A comment on the mechanism involved in the various reactions is also given. (c) 2005 Elsevier B.V. All rights reserved.