Monosaccharification of rice hulls by enzymatic hydrolysis combined with hot-compressed water (HCW) treatment was investigated. First, rice hulls were extracted with HCW at 200 degrees C and 3.0 MPa using a percolator type reactor to remove the components other than cellulose. Next, the residual rice hulls were treated with HCW at 280 degrees C and 10 MPa to decompose the cellulose into water-soluble saccharides. The resulting aqueous solution was converted to monosaccharides by enzymatic hydrolysis, and glucose was produced at a yield of 68.1 wt% on cellulose base after a digestion time of 48 h. However, the residual rice hulls were only slightly saccharified and the conversion ratio was only 9.8 wt%.