The enzymatic degradation of polysaccharides to monosaccharides is an essential step in bioconversion processes of lignocellulosic materials. Alkali treated brewers spent grain was used as a model substrate for the study of cellulose and hemicellulose hydrolysis by Fusarium oxysporum enzyme extract. The results obtained showed that cellulose and hemicellulose conversions are not affected by the same factors, implementing different strategies for a successful bioconversion. Satisfactory cellulose conversion could be achieved by increasing the enzyme dosage in order to overcome the end-product inhibition, while the complexity of hemicellulose structure imposes the presence of specific enzyme activities in the enzyme mixture used. All the factors investigated were combined in a mathematical model describing and predicting alkali treated brewers spent grain conversion by F. oxysporum enzyme extract. (C) 2010 Elsevier Ltd. All rights reserved.