Carbonate was added into a co-culture of glucose and fresh leachate under alkaline condition to enhance batched acidogenesis and fermentative hydrogen production simultaneously. Results indicated carbonate has positive effect on both H-2 production and acetic acid generation. The highest hydrogen yield (about 1.40 mol/mol glucose) was obtained at [CO32-] = 280 mg/L with pH 8.0 and [CO32-] = 560 mg/L with pH 9. The dominant liquid metabolites were ethanol, acetic and butyric acid. The highest total volatile fatty acid yield (0.38 g/g glucose) was achieved at [CO32-] = 560 mg/L with pH 9. In this case, the acetic acid yield reached 0.13 g/g glucose. Verification tests using simulated wastewater as substrate were also carried out at pH 9. Results demonstrated calcium ions inhibit hydrogenogens activity while carbonate addition can alleviate the suppression effect caused by Ca2+. (C) 2012 Elsevier Ltd. All rights reserved.