A supercritical water pretreatment was applied to cellulose dissolution and hydrolysis. The effects of temperature, residence time, and ratio of solid/liquid phase on the cellulose dissolution and sugar conversion were investigated. The results showed that cellulose could dissolve completely in a short time at 380 ℃ and higher temperature. The reaction temperature has significant effect on consequent hydrolyzation and sugar conversion in the range of 374～386 ℃, and the highest concentration of oligosaccharides and hexoses was obtained around the critical point. On the other hand, these products were also decomposed rapidly under the supercritical condition with the extending of reaction time. The ratio of initial solid/liquid phase affects the cellulose hydrolyzation markedly as well. The best results were obtained with 40 mg cellulose/2.5 mL water at 380 ℃ and 16 s, affording oligosaccharide recovery above 29%, or 80 mg cellulose/2.5 mL water at 380 ℃ and 18 s, affording hexose recovery above 39%.

Key words: cellulose, supercritical water, hydrolyzation, oligosaccharide, glucose