Catalytic depolymerization of empty fruit bunch (EFB)-derived organosolv lignin, which is free of ash and catalyst-poisoning sulfur, is performed using supported metal catalysts. Without the improved reaction activity in the presence of supercritical solvents, water and ethanol in this study, at the subcritical conditions, Hp-supported Ru catalyst achieved 16.5% yield of small molecule phenolic hydrocarbons, including guaiacol, 4-methylguaiacol, 4-ethylguaiacol, cerulignol, and iso-eugenol, and produced degraded lignin polymer with 63% decreased weight-average molecular weight based on polystyrene-calibrated gel permeation chromatography results. The catalytic depolymerization activity was determined by the quantity of acid sites on the catalysts; however, the presence of metal nanoparticles is required to supply hydrogen atoms to the reaction system, which particles improve the catalytic depolymerization activity. The structure of organosolv lignin prepared by extraction using a mixture of ethanol and water was also studied using GPC and NMR results, which indicated that a possibly linear polymer composed of phenolic monomers with two or fewer linking functionalities. (C) 2016 Elsevier B.V. All rights reserved.