In the process of producing H(2) from lignocellulosic materials, inhibitory compounds could be potentially formed during pre-treatment. This work experimentally investigated the effect of lignocellulose-derived inhibitors on growth and hydrogen production by Thermoanaerobacterium thermosaccharolyticum W16. Representative compounds presented in corn stover acid hydrolysate were added in various concentrations, individually or in various combinations and subsequently inhibitions on growth and H(2) production were quantified. Acetate sodium was not inhibitory to T. thermosaccharolyticum W16, rather than it was stimulatory to the growth and H(2) production. Alternatively, furfural, hydroxymethylfurfural (HMF), vanillin and syringaldehyde were potent inhibitors of growth and hydrogen production even though these compounds showed inhibitory effect depending on their concentrations. Synergistic inhibitory effects were exhibited in the introduction of combinations of inhibitors to the medium and in hydrolysate with concentrated inhibitors. Fermentation results from hydrolysates revealed that to increase the efficiency of this bioprocess from corn stover hydrolysate, the inhibitory compounds concentration must be reduced to the levels present in the raw hydrolysate. Crown Copyright (C) 2009 Published by Elsevier Ltd on behalf of Professor T. Nejat Veziroglu. All rights reserved.