Ground wheat (21 g) was subjected to batch solid state dark fermentation for bio-hydrogen production. Clostridium acetobutylicum (B-527) was used as the culture of dark fermentation bacteria at mesophilic conditions. Effects of moisture content on the rate and yield of bio-hydrogen formation were investigated. The highest CHF (1222 ml), hydrogen yield (63 ml H-2 g(-1) starch), formation rate (10.64 ml H-2 g(-1) starch h(-1)) and specific hydrogen formation rate (0.28 ml H-2 g(-1) biomass h(-1)) were obtained with a moisture content of 80%. Nearly complete starch hydrolysis and glucose fermentation were achieved with more than 80% moisture content and the highest substrate conversion rate (21.9 mg L-1 h(-1)) was obtained with 90% moisture content at batch solid state fermentation producing volatile fatty acids (VFA) and H-2. (C) 2017 Hydrogen Energy Publications LLG. Published by Elsevier Ltd. All rights reserved.