The biohydrogen production performance was investigated in both of the continuously stirred anaerobic bioreactor (CSABR) and the egg-shaped external circulation hydrogen production bioreactor (EEC-HPBR) in this study. It was found that the biohydrogen production rate in EEC-HPBR was higher than that in the CSABR when the hydraulic retention time (HRT) was varied from 8 to 2 h. The hydrodynamic properties such as the bubble diameter, bubble rising velocity and phase holdups were carried out in a 2-D bioreactor to simulate the real 3-D bioreactor. The seed sludge in the 2-D bioreactor was taken from the CSABR at the same operational condition with a substrate concentration of 20 g total sugar/L. It was found that the average bubble diameter was 0.33 mm with a mild change during the HRT from 8 to 1 h. The bubble rising velocity against the substrate feeding rate increased linearly. The gas (epsilon(g)) and solid (epsilon(s)) phase-holdups increased with a decrease of the liquid (epsilon(l)) phase-holdup when HRT was shortened. The flow regime and mass transfer effects will change according to the bubble formation in the bioreactor. Finally, the study demonstrates that the parameters such as bubble diameter, bubble rising velocity and phase-holdups support bioreactor scale-up. Also this applies to the conditions for steady-state operations of the hydrogen production bioreactor from sugary wastewater. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.