The production of hydrogen through the gasification of glucose as a biomass model compound and ethanol was examined with 5wt% ruthenium supported carbon catalysts by a flow-type reactor in supercritical water around 673 K at 10 - 30 MPa. In the gasification of glucose, the gas products were hydrogen, methane, carbon dioxide and carbon monoxide. The yield of gases increased with increasing in contact time (W/F [g-cat s/mol]), while the amount of organic carbon concentration in the liquid effluent decreased. At W/F of 260000, the glucose was almost gasified regardless of pressure. The gasification of glucose effectively proceeded the ruthenium supported carbon catalyst. On the other hand, the gas production rate increased with increasing pressure less than 25 MPa and then decreased at W/F of 26000. In the gasification of ethanol, the gas products were hydrogen, methane and carbon dioxide. The yield of gases increased with increasing W/F the same as the gasification of glucose. The gas production rate, especially hydrogen decreased with increasing pressure. The increase in pressure probably leaded to both the enhancement of reaction due to the increase of reactants and the suppression of the reaction such as gasification that increases the number of molecules by Le Chatelier’s principle. The pressure dependence on the supercritical water gasification was determined by both advantageous and disadvantageous factors.