At a packing ratio of 12%, the hydrogen production rate and hydrogen yield reached maximum of 345 mL H2/L-POME h and 0.35 L H2/g CODadded,respectively, which were higher compared to those attained at 4% and 8%. This suggested that increases in biomass loading increase the hydrogen production rate. However,the hydrogen production rate and yield decreased, when the packing ratio of immobilized-cell beads in the reactor increased from 12 to 16%.