Mo2C/ZrO2 was investigated as catalyst for hydrodeoxygenation (HDO) of phenol in 1-octanol as a simplified bio-oil model system in a fixed-bed setup at 100 bar. Mo2C/ZrO2 selectively converted phenol to benzene above 320 degrees C. During long-term testing, limited stability of the catalyst was observed, with the conversion of 1-octanol and phenol decreasing from 70% to 37% and from 37% to 19%, respectively, over 76 h of operation. Repeating the experiment but also co-feeding 30% water, the catalyst deactivated completely within 12 h of operation. Thermodynamic calculations and in situ XRD analysis showed that Mo2C is transformed to MoO2 in the presence of water at the given conditions, and this was probably the source of deactivation in the experiments. Thus, Mo2C-based catalyst for HDO seems interesting, but requires further stabilization or regeneration of the carbide phase as bio-oil contains high levels of water and water is a by-product during HDO. (C) 2015 Elsevier Inc. All rights reserved.