Effects of in-house prepared CoMo catalysts supported on various nano-structured materials (activated carbon, [y-alumina, HZSM-5, MCM-41 and SBA-15) and a commercial catalyst of Ru/C were compared for hydrodeoxygenation (HDO) of fast pyrolysis oil (P0) in supercritical ethanol at 300 and 350 degrees C. All catalysts proved to be effective for significantly reducing the molecular weight of the PO by HDO treatment at 350 degrees C. Although Ru/C catalyst produced the highest oil yield at both temperatures (66.6 wt% at 300 degrees C and 61.0 wt% at 350 degrees C) with the lowest and negligible coke formation (<1 wt%), the catalyst is very expensive and difficult for regeneration, so it is not a viable catalyst for bio-oil upgrading on a large scale. Among all the supported CoMo catalysts, CoMo/MCM-41 produced the highest yield of oil products (light oil (OL) + heavy oil (HO)) of the highest H/C molar ratio. With this catalyst, the oil yield attained 61.9 wt% at 300 degrees C and 57.8 wt% at 350 degrees C, and the spent catalyst after regeneration produced almost the same oil yields as the fresh one. In addition, CoMo catalysts supported on MCM-41 and SBA showed better resistance to coke/carbon deposition in the HDO process, compared with CoMo catalysts supported on HZSM-5 and Al2O3. (C) 2015 Elsevier B.V. All rights reserved.