Corn fibre is a co-product of the corn wet milling industry which is usually marketed as a low value animal feed ingredient. Approximately 4.7 x 10(6) dry tons of this material are produced annually in the United States. The fibre is composed of kernel cell wall fractions and residual starch which can all potentially be hydrolysed to a mixture of glucose, xylose, arabinose and galactose. A sequential saccharification of polysaccharides in corn fibre by a treatment with dilute sulphuric acid at 100-160 degrees C followed by partial neutralization and enzymic hydrolysis with mixed cellulase and amyloglucosidase enzymes at 45 degrees C was investigated. The sequential treatment achieved a high (approximately 85%) conversion of all polysaccharides in the corn fibre to monomeric sugars. These hydrolysates were in most cases fermentable to ethanol by the recombinant bacterium Escherichia coli KO11.