Abstract: An improved process for the production of linear alternating polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon comprises(1) contacting carbon monoxide and ethylenically unsaturated hydrocarbon monomers in a reactor under polymerization conditions in the presence of a liquid reaction diluent and a catalyst composition formed from a compound of palladium, the anion of a strong non-hydrohalogenic acid and a bidentate ligand of phosphorus,(2) removing a portion of the resulting suspension of polymer in reaction diluent from the reactor, passing a part of that portion from the reactor system and passing the remainder of the portion through means for applying mechanical shear and back to the reactor, and(3) removing unreacted monomers from the gas cap in the reactor, mixing the removed unreacted monomers with carbon monoxide and ethylenically unsaturated hydrocarbon and passing the mixture through the means for applying mechanical shear and back to the reactor.