The effect of co-culturing C. beijerinckii and C. saccharoperbutylacetonicum for H-2 production using mono-and co-substrates of glucose, starch, and cellulose was assessed. Monod kinetic parameters (K, maximum specific substrate utilization rate; and K-s, half-saturation constant) of the C. beijerinckii, C. saccharoperbutylacetonicum, and the co-culture were determined. Co-cultures utilizing glucose competed for the substrate, but showed enhancement for utilizing starch. The maximum values for K on glucose and starch were 0.48 g substrate/gVSS. h achieved by C. saccharoperbutylacetonicum mono-culture and 0.39 g substrate/gVSS. h achieved by the co-culture, respectively. The average Ks for all mono-and co-culture experiments was 0.93 +/- 0.03 g/L. Acetate, butyrate, and propionate were the main fermentation products for all experiments. Maximum H-2 production yields on glucose (2.69 mol/mol(glucose)) and starch (1.07 mol/mol(hexose)) were achieved by C. beijerinckii and C. saccharoperbutylacetonicum mono-cultures, respectively; however, neither culture was able to degrade cellulose as a mono-substrate. (C) 2017 Elsevier Ltd. All rights reserved.