Poultry slaughterhouse sludge from chicken processing wastewater treatment plant was tested for their suitability as a substrate and inoculum source for fermentation hydrogen production. Dual digestion of poultry slaughterhouse sludge was employed to produce hydrogen by batch anaerobic self-fermentation without any extra-seeds. The sludge (5% TS) was dual digested by aerobic thermophilic digestion at 55 degrees C with the varying retention time before using as substrate in anaerobic self-fermentation. The best digestion time for enriching hydrogen-producing seeds was 48 h as it completely repressed methanogenic activity and gave the maximum hydrogen yield of 136.9 mL H(2)/g TS with a hydrogen production rate of 2.56 mL H(2)/L/h. The hydrogen production of treated sludge at 48 h (136.9 mL H(2)/g TS) was 15 times higher than that of the raw sludge (8.83 mL H(2)/g TS). With this fermentation process, tCOD value in the activated sludge could be reduced up to 30%. (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.