A special type of bioreactor was designed and tested in order to improve the bioethanol production from lignocellulosic materials via enzymatic hydrolysis and fermentation. The reactor consists of two chambers kept at different temperatures and separated by a porous medium, through which the solutes can diffuse. The reactor was tested using as substrate wheat straw previously steam exploded and detoxified. The yields of cellulose hydrolysis and glucose fermentation obtained using this reactor were compared to those obtained by simultaneous enzymatic hydrolysis and fermentation (SSF) carried out in only one vessel. The results showed that a significant increase in the ethanol yield (20%) can be achieved by using this bioreactor. An additional advantage of the reactor is the confinement of the solid lignin in one chamber, allowing a simplified separation process between broth and unreacted residue. (C) 2012 Elsevier Ltd. All rights reserved.