Under HTL conditions, deoxygenation can, to a certain extent, be realized without hydrogen. This is often stated as one of the major advantages of this technique, but apparently, the products would be different than those obtained by catalytic hydrotreating. Depending on the operating conditions and the feedstock, oxygen contents of the hydrophobic phases as low as 4-7 wt.% are reported in the literature.32,33 However, such low oxygen content is rare and the average reported oxygen concentration is 15-20 wt.%. Oxygen removal under the HTC conditions occurs via the following reactions: dehydration, decarboxylation and decarbonylation. CO added to the reactor or formed in the reactions appears largely converted to CO2 in the water gas shift or reduction reactions. Consequently, the net effect of deoxygenation during the HTC is the CO2 and HjO formation, the first one being favourable from an energetic point of view. It has been shown that the reactions of mono-sugars in hot compressed water are dominated by dehydration reactions,1 resulting in significant water production.