The use of unprotected maleic acid (MA) as a chain transfer agent (CTA) during ring-opening metathesis polymerization (ROMP) of cis-cyclooctene (COE) to provide carboxy-telechelic PCOE with an average degree of polymerization (N) was described. Four samples were initially prepared by polymerizing COE in tetrahydrofuran at 40°C with varying concentrations of maleic acid (MA). The value of the triplet coupling constant attributed to the olefinic protons suggests coupling to the methylene protons at 2.23 ppm. The spectra for carboxyl terminal PCOE reveal only one distinct signal for each of the protons corresponding to an exclusive trans configuration about the terminal double bond adjacent to the carboxyl end group. Hydrogenation with Wilkinson's catalyst [tris(triphenylphosphine)rhodium(I) chloride] provides quantitative saturation of backbone double bonds without reduction of carboxyl groups.