Abstract The catalytic conversion of sugars (glucose and fructose) to furan compounds (HMF and furfural) was studied under hot compressed water (HCW) conditions. The effect of catalyst types (homogeneous acid (H3PO4) and base (NaOH)), and starting materials (monosaccharide and cellulose) on furan yields was investigated. It was found that at 200 °C, phosphoric acid showed great catalytic activity on the production yield of HMF from dehydration of the sugars, when compared with NaOH. Cellulose is composed of glucose units, and would first be hydrolyzed and then dehydrated to furans. The optimum condition for hydrolysis/dehydration was observed under the acid-catalyzed conditions with the reaction temperature of 230 °C and reaction time of 5 minutes, at which the yields of sugar and furan compounds were achieved at 23.0 and 7.5%, respectively.