Aqueous liquefaction of biomass samples was carried out in an autoclave in the reaction temperature range of 550 - 650 K. In this study, the maximum liquid yield (49%) was obtained from the spruce wood powder at 650 K. It is clear that the yield of liquid products increase with increasing liquefaction temperature for each biomass sample. In general, composition of liquefaction products depends on structural composition of the sample. The yield of water soluble fraction increases with increasing lignin content of the biomass sample, and the highest water soluble fraction (WSF) yield was obtained for hazelnut shell at liquefaction temperature around 650 K, which was about 21%. The yield of heavy oil generally decreases with increasing lignin content of the biomass sample, and the highest heavy oil yield was obtained for beech wood at liquefaction temperature around 650 K, which was about 28%. The yield of acetone insoluble fraction ( residue) decreases with increasing liquefaction temperature for all of runs.