Reactions of D-fructose in water at high temperatures (350 and 400 degrees C) and pressures (up to 100 MPa) were studied using a flow reactor. High temperature (400 degrees C) and moderate pressure (40MPa) conditions enhanced the yields of retro-aldol related products such as glyceraldehyde, dihydroxyacetone and pyruvaldehyde. High temperature, high pressure conditions enhanced retro-aldol reactions and water related reactions such as hydrolysis and dehydration. Comparison between D-fructose and D-glucose experiments showed that higher yields for 5-HMF were obtained starting from D-fructose than D-glucose. Surprisingly, higher yields of furfural were obtained starting from D-glucose than from D-fructose which is contrary to reaction pathways in the hydrothermal literature. Based on the experimental results, a possible reaction scheme is proposed for water catalyzed (i) benzilic acid rearrangement reactions from pyruvaldehyde to lactic acid and (ii) retro-aldol reaction from D-glucose to furfural. (c) 2007 Elsevier B.V. All rights reserved.