AbstractOrganosolv lignin degradation was carried out through hydrogenolysis routes with SO42-/ZrO2 as the catalyst. Structural characterization and antioxidant activity of organosolv lignin samples were investigated; the antioxidant activity of the organosolv lignin was compared with that of soda lignin. Results showed that the active functional groups contents of organosolv lignin were increased, and the antioxidant activity of organosolv lignin was improved. The total hydroxyl and phenolic hydroxyl group contents of organosolv lignin were increased by 15.81% and 26.55%, respectively, and the Mw was decreased from 5739 g/mol to 4499 g/mol. The IC50 of organosolv lignin on DPPH radicals scavenging rate, ABTS+ radicals scavenging rate, and reducing power were decreased by 18.91%, 18.08%, and 8.48%, respectively. The catalyzed organosolv lignin can be used as a natural antioxidant for functional food or in cosmetic and polymeric materials.