In supercritical water oxidation of glucose, the effect of oxygen concentration on the production rate of gaseous components (CO, CO2, H-2 and CH4) was examined at 400-470 degreesC and 18.5, 25..5 MPa with residence times of less than 30 sec in a flow- type reactor. Hydrogen peroxide was used as an oxidant. Oxygen was produced by hydrogen peroxide decomposition. Oxygen concentration was varied from 50 to 250% compared with nominal stoichiometric oxygen concentration. The experimental results revealed that the oxygen concentration did not signtficantly influence the yields of gaseous components, and that the amounts of gaseous products increased with residence time up to 5 sec and then reached a plateau. Apparent rate analysis was carried out based on the assumption that the overall production rate of carbon-containing gaseous speacies is proportional to glucose concentration. The result suggests that the initial stage of oxidation up to 5 sec of residence time was described by first-order kinetics. An Arrhenius plot of the obtained apparent first-order rate constant showed that the ratio of frequency factors for oxygen concentrations of 100 and 200% was almost equivalent to the oxygen concentration ratio.