Abstract: The present invention relates to a process for producing cycloalkenamer-containing compositions, comprising the steps of: a) converting at least one cycloalkene by ring-opening metathetic polymerization to obtain a polyalkenamer-containing product mixture, and b) working up the product mixture to remove monomers and oligomers of the cycloalkenes to obtain the polyalkenamer-containing composition by extraction with CO2, whereby the polyalkenamers are polymers of cycloalkenes which comprise at least five cycloalkane monomer units, wherein the extraction comprises at least two stages: b0) an extraction with liquid CO2, then b1) an extraction with supercritical CO2, then b2) an extraction with gaseous CO2, then b0) an extraction with liquid CO2, then and then b3) an extraction with supercritical CO2.