A thermodynamic analysis was performed for hydrogen production from ethanol reforming and oxidation in supercritical water (SCW) conditions. The minimization of Gibbs free energy was used to calculate the equilibrium composition to investigate the effect of operating conditions, pressure, temperature, H2O2:EtOH molar ratio and H2O:EtOH molar ratio, on product yields. The theoretical results indicated that the yields of hydrogen and carbon monoxide decreased as the pressure increased but a H2/CO ratio at atmospheric pressure was lower than that at SCW conditions. High temperatures increased the efficiency of hydrogen production although the amount of carbon monoxide also increased. The presence of oxygen led to great decreases in methane oxidized to carbon dioxide and water. The spending of some hydrogen oxidized to water resulting in a lower hydrogen yield. High H2O:EtOH ratios increased the yields of hydrogen and carbon dioxide but decreased the methane and carbon monoxide production. It is possible to conclude that high temperature, high H2O:EtOH ratio and low addition of oxygen should lead to best results in the SCWO of ethanol.