The fermentation of glucose, cheese whey and the mixture of glucose and cheese whey were evaluated in this study from two inocula sources (sludge from a UASB reactor for swine wastewater treatment and poultry slaughterhouse) for hydrogen production in continuous anaerobic fluidized bed reactors (AFBR). For all fermentations, a hydraulic retention time (HRT) of 6 h and a substrate concentration of 5 g COD L-1 were used. In glucose fermentation, the maximum hydrogen yield (HY) was 1.37 mmol H-2 g(-1) COD. The co-fermentation of the cheese whey and glucose mixture was favorable for the concomitant production of hydrogen and ethanol, with yields of up to 1.7 mmol H-2 g(-1) COD and 3.45 mol EtOH g(-1) COD in AFBR2. The utilization of cheese whey as a sole substrate resulted in an HY of 1.9 mmol H-2 g(-1) COD. Throughout the study, ethanol fermentation was evident. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.