Biological processes are an environmentally friendly technology for producing hydrogen from renewable resources such as biomass. However, biological fermentation has low yield and low energy recovery for hydrogen production. To increase hydrogen production from biomass, we have recently developed a new method to produce hydrogen from organic matter based on a modified microbial fuel cell (MFC). We report here that by optimizing the reactor configurations and operation conditions the hydrogen yield increased to 3.9 mol H2/mol acetate with an average of current efficiency of 99.6%. Hydrogen production rate was 1300 L H2/d-m3-reactor volume with COD removals of 90-97%. This hydrogen production rate is ∼70 times higher than that previously reported.