Thermal conversion of biomass to liquids can proceed via non-pyrolytic processes, in which the feedstock is directly heated in a liquid medium that may or may not interact with the biomass (Cheng et al. 2010; Klass 1998; Titirici et al. 2007). Low temperature and atmospheric pressure in the presence of a solvent with acidic or basic catalysts can be used, but these solvents have to be recycled, rendering the process energetically and financially costly. The use of higher temperatures and pressures in water have shown promising results and recently an increase of inter­est regarding hot-compressed or sub-/supercritical water technologies (hydrother­mal technologies) for biomass conversion has appeared (Peterson et al. 2008). Hydrothermal processing can be divided into three main regions, namely: lique­faction, catalytic gasification and high-temperature gasification, depending on the

temperature and pressure conditions (Klingler and Vogel 2010). The production of biocrude, aqueous organics, combustible gases (H2, CO, CO2, CH4) and light hydrocarbons is expected.