tSupercritical Water Gasification (SCWG) is a promising way of directly producing hydrogen at high pres-sures and with a short reaction time. In this work, the use of SCWG in the conversion of biomass wasinvestigated through a mathematical model based on the thermodynamic equilibrium of the reactionsinvolved in the process. The numerical model applied was based on the literature and evaluated by thereproduction of experimental data. The effects of temperature, pressure and several sources of biomass(alcohols, aldehydes, carbohydrates, phenols) were evaluated, as well as the limitations of the model.The results showed that the model was able to represent well the experimental data, with standarddeviations of the dry gas composition for H2and CO2being 6.5 % and 2.82 % for ethanol and glycerol,respectively. Predictions performed with guaiacol, phenol and glucose indicated, given a specific scenario,concentrations of H2at around 68, 67 and 66 %, respectively2026-03