Rice hulls, a complex lignocellulosic material with high lignin (15.38 ( 0.2%) and ash (18.71 ( 0.01%) content, contain 35.62 ( 0.12% cellulose and 11.96 ( 0.73% hemicellulose and has the potential to serve as a low-cost feedstock for production of ethanol. Dilute H 2 SO 4 pretreatments at varied temperature (120-190 ยฐC) and enzymatic saccharification (45 ยฐC, pH 5.0) were evaluated for conversion of rice hull cellulose and hemicellulose to monomeric sugars. The maximum yield of monomeric sugars from rice hulls (15%, w/v) by dilute H 2 SO 4 (1.0%, v/v) pretreatment and enzymatic saccharification (45 ยฐC, pH 5.0, 72 h) using cellulase, ฮฒ-glucosidase, xylanase, esterase, and Tween 20 was 287 ( 3 mg/g (60% yield based on total carbohydrate content). Under this condition, no furfural and hydroxymethyl furfural were produced. The yield of ethanol per L by the mixed sugar utilizing recombinant Escherichia coli strain FBR 5 from rice hull hydrolyzate containing 43.6 ( 3.0 g fermentable sugars (glucose, 18.2 ( 1.4 g; xylose, 21.4 ( 1.1 g; arabinose, 2.4 ( 0.3 g; galactose, 1.6 ( 0.2 g) was 18.7 ( 0.6 g (0.43 ( 0.02 g/g sugars obtained; 0.13 ( 0.01 g/g rice hulls) at pH 6.5 and 35 ยฐC. Detoxification of the acid-and enzyme-treated rice hull hydrolyzate by overliming (pH 10.5, 90 ยฐC, 30 min) reduced the time required for maximum ethanol production (17 ( 0.2 g from 42.0 ( 0.7 g sugars per L) by the E. coli strain from 64 to 39 h in the case of separate hydrolysis and fermentation and increased the maximum ethanol yield (per L) from 7.1 ( 2.3 g in 140 h to 9.1 ( 0.7 g in 112 h in the case of simultaneous saccharification and fermentation.