Oligomeric and monomeric xylose concentrations were measured in the effluent during all the FT experiments, but at temperatures beyond 200 °C, significant degradation of xylan to unknown products was observed.  However, in all cases, total xylan removed was proportional to lignin and acetate release although increasing the reaction temperatures from 200 to 230 °C did not significantly enhance the kinetics of either xylan, lignin or acetate removal. These results suggest that cleavage of ester bonds, de-lignification and removal of xylan occur simultaneously. Since xylan is covalently linked to lignin via ferulic ester linkages, it seems likely that under hot water FT conditions, cleavage of this ester bond occurs and facilitates xylan release. Melting and mobilization of lignin also likely contribute to the process of xylan release. Through this ongoing work, we are developing a better mechanistic understanding of lignin-xylan interactions at high temperatures.