Hydrogen (H-2) production potential of water hyacinth (WH) and beverage wastewater (BW) mixture in powder and pellet form at various combination ratios were evaluated. Batch co-fermentation results showed peak biogas production of 105.5 mL and H-2 production of 55.6 mL at the combination ratio of 1.6 g WH and 2.4 g BW in pellet form. With the same ratio in pellet form, the maximum H-2 production rate 542 mL H-2/L-d, maximum specific H-2 production rate 869 mL H-2/g VSS-d and H-2 yield 13.65 mL/g feedstock were obtained, and were 88, 88 and 34% higher than its powder form. The predominant soluble metabolite was acetate in the concentration of 1059-2639 mg COD/L (40-79% of total metabolites) in most runs during co-fermentation of mixed feedstock. Carbon-to-nitrogen ratio and the physical form of the combined feedstock are essential criteria for optimum H-2 production. Co-fermentation also alleviates the waste disposal problem of the industries. (C) 2012 Elsevier Ltd. All rights reserved.