The global flour industry produces 96 million ton/year of wheatfeed, which is mainly used for animal feed. This co-product is high in carbohydrates and potentially a significant substrate for biohydrogen production. A 10 1 bioreactor, inoculated with sewage sludge, was operated on wheatfeed (10 g l(-1)) at pH 5.5 and 35 degrees C in batch and semi-continuous mode (15 h hydraulic retention time (HRT)). Wheat-feed hydrolysate was also investigated in continuous mode (15 h HRT). NaOH-H(2)O(2) treatment of 25 g l(-1) wheatfeed resulted in hydrolysate containing on average 8.1 g l(-1) total sugar. Hydrogen yields of 64 and 56 m(3) H(2) per ton dry weight were produced from wheatfeed in batch and 56 m(3) H(2) per ton dry weight of wheatfeed in semi-continuous mode. Hydrogen yields from hydrolysate were only 22 and 31 m(3) H(2) per ton dry weight, (or 0.9 mol H(2) per mol hexose degraded, assuming all sugar is hexose). Fermentation of unhydrolysed wheatfeed is therefore recommended. It is calculated that approximately 264 m(3)/ton of CH(4) can be produced from a subsequent anaerobic digestion stage. The biohydrogen produced (diesel equivalents) from the 1.2 million ton/year of wheatfeed in the UK would be more than twice that required for transportation by the UK flour industry. (C) 2007 Elsevier Ltd. All rights reserved.