Treated activated carbon (T-AC) was found to be highly effective for fermentative hydrogen production due to its highly porous structure. The addition of T-AC at 8.3-33.3 g/L in batch experiments increased the hydrogen production rate and yield from 0.8 to 1.8 mL of H2/h and from 1.24 ± 0.13 to 2.60 ± 0.21 mol of H2/mol of sucrose, respectively. The high activity of T-AC was attributed to a greater porosity and active sites as compared to commercial activated carbon. The use of T-AC reduced the inhibitory effect of butyric acid with selective adsorption of butyric acid over metabolite products. Moreover, T-AC showed a highly durable performance for three repeated cycles for hydrogen production. The hydrogen production increased by 73% as compared to the control for the first cycle and dropped by 32% after three consecutive cultivation cycles. It is postulated that a highly porous surface and affinity of T-AC may provide sites for volatile fatty acids adsorption, thereby reducing the inhibitory effect on hydrogen-producing bacteria. © 2014 American Chemical Society. -------------------------------------------------------------------------------- ; Fermentative hydrogen production; Hydrogen producing bacteria; Hydrogen production rate; Inhibitory effect; Porous structures; Selective adsorption; Treated activated carbons