Toxicity renders certain industrial effluents unfit for recovering its bioenergy content. An enriched single strain, Clostridium butyricum, was herein applied to fermentatively produce hydrogen from glucose in the presence of 200–1500mgL −1 of phenol. The enriched C. butyricum yielded hydrogen at approximately 1.4molH 2 mol −1 glucose in the presence of 200–400mgL −1 phenol. Significant inhibition of cell metabolism was noted at phenol concentration >1000mgL −1 . During glucose fermentation, phenol dosed at 200–400mgL −1 was partly co-degraded. Ethanol and acetate were the primary metabolites, whose yields increased with increasing phenol concentration. The present results revealed the potential to harvest hydrogen from a toxic (phenol-containing) wastewater.