Catalytic hydrothermal treatment of wood biomass was performed at 280° C for 15 min in the presence of alkaline solutions (NaOH, Na2CO3, KOH and K2CO3). Oil products were extracted from both liquid and solid portion by different solvents and analyzed individually. The effect of base solutions on the yield of oil products and composition of oils obtained at different stages were discussed in detail. Based on the conversion and yield of liquid products, the catalytic activity can be ranked as follows: K2CO3 > KOH > Na2CO3 > NaOH. In thermal run, the yield of solid residue was about 42% whereas it was 4.0% in the presence of K2CO3. Catalytic hydrothermal treatment of biomass produced mainly phenolic compounds. In thermal run, furan derivatives were observed whereas these compounds could not be observed in catalytic runs. The volatility distribution of hydrocarbons (ether extract) was characterized by using C-NP gram and it showed that the majority of hydrocarbons for all runs including thermal were distributed boiling point range of n-C-11. The products from hydrothermal treatment of wood biomass were analyzed using GC-MS, H-1 NMR, C-13 NMR, TOC and ion chromatograph. © 2005 Elsevier B.V. All rights reserved.