AbstractThe current Chinese Standard (GB5889-86 1986) for wet chemistry determination assumes that there is no temperature degradation of sugars during hot water extraction. There is therefore a need to quantify this level of error and propose possible solutions for future revisions. This research was performed to investigate the thermal resistance of polysaccharides in common fibrous materials. A two-factor, two-level experimental design was employed, in which pre-oven drying and water bath temperature were controlled and changes in extractive content were measured. The thermodynamic equations for polysaccharide thermal degradation in ramie and wood were calculated. High-performance liquid chromatography (HPLC) was employed to identify monosaccharide changes during the process. This study found that polysaccharides in fibrous materials have considerable thermal degradation during oven drying at 100 °C and hot water treatment. Lower temperature combinations are recommended during hot water extractive testing when sugar analysis is to be subsequently performed.