The aim of this study was to determine the optimal conditions for dark fermentation using agro-industrial liquid wastewaters mixed with sweet sorghum stalks (i.e., 55% sorghum, 40% cheese whey, and 5% cow manure). Batch experiments were performed investigate effect controlled pH (5.0, 5.5, 6.0, 6.5) on production bio-hydrogen volatile fatty acids. According obtained results, maximum hydrogen yi...