Determination of hydroxyl groups were conducted on heavy hydrocarbon fractions including lignin degradation products. The acetylation was conducted using trifluoroacetic anhydride and pyridine-d_5 in chloroform-d followed by the determination of trifluoromethyl group by ^<19>F-NMR. Phenolic and alcoholic hydroxyl groups were distinguished by the chemical shifts. The amounts of the hydroxyl groups were well agreed with the results by an average molecular structural analysis.
