This article presents a system model for the process of gasification of biomass model compounds in supercritical water. Supercritical water gasification of wet biomass (water content of 70 wt% or more) has as the main advantage that conversion may take place without the costly drying step. The thermodynamic model is generated in ASPEN 12.1 under the assumption of chemical equilibrium and using model compounds to represent the organics in the wet biomass. The research focuses on predicting the influence of several parameters on the thermal efficiency of the process. One of the important parameters under investigation is the heat exchanger effectiveness. The possibility of tailoring the product gases and in situ CO2 capturing using water are also modeled and described. (C) 2011 Elsevier B.V. All rights reserved.