The hydrothermal liquefaction of biomass was carried out using sodium perborate monohydrate (NaBO3 center dot H2O) at 250,300 and 350 degrees C. The effects of temperature and additive concentrations on the product distributions were investigated. NaBO3 center dot H2O was found to be very effective for the hydrothermal liquefaction of biomass at 300 and 350 degrees C. The use of NaBO3 center dot H2O in the liquefaction of woody biomass increased the yields of bio-oils and decreased the solid residue yields at 300 and 350 degrees C. All concentrations of NaBO3 center dot H2O showed high catalytic performance at 300 and 350 degrees C. The identified compounds in bio-oils (light bio-oils and heavy bio-oils) were mostly oxygenated hydrocarbons for both the thermal and NaBO3 center dot H2O runs. Furfural, 5-methyl furfural, and 5-(hydroxymethyl)furfural were only observed in the thermal run. Most of the identified compounds in the light bio-oils obtained from the thermal and NaBO3 center dot H2O runs were phenolic compounds. The highest heating value of the resultant heavy bio-oils was approximately 32 MJ/kg, which was obtained from the hydrothermal liquefaction of biomass at 350 degrees C with NaBO3 center dot H2O. (C) 2013 Elsevier B.V. All rights reserved.