The objective of this study was to investigate the effects of water tolerant Lewis acids (i.e., In(OTf)(3), Yb(OTf)(3) and InCl3) on bio-oil and solid residue yields. For this purpose, poplar wood was liquefied at 300 degrees C with a residence time of 10 min without and with, water tolerant Lewis acids in various concentrations from 0.5 to 10 wt% under hydrothermal conditions. The use of water tolerant Lewis acids had negative effects on bio-oil yields. The bio-oil from the run without a catalyst had a value of 17.50 wt% at 300 degrees C, 10 min. The highest bio-oil yields under identical conditions were the following: 14.27 wt%, 1337 wt% and 12.42 wt for Yb(OTf)(3) (with a concentration of 0.5 wt% of the raw material), In(OTf)(3) and InCl3 (with concentrations of 1 wt% of the raw material). The concentrations of catalysts used in the experiments had significant effects on both bio-oil and solid residue yields. An increase of catalyst concentrations resulted in a decrease in bio-oil yields. The catalysts changed neither the molecular nor the elemental compositions of bio-oils and solid residues significantly. The prominent compounds in bio-oils from all runs including the run without a catalyst were phenol, 2,6-dimethoxyphenol; and 2-methoxyphenol. (C) 2015 Energy Institute. Published by Elsevier Ltd. All rights reserved.