1. Introduction -- 2. Microbiology -- 3. Hydrogen production processes -- 4. Biohydrogen feedstock -- 5. Molecular biology of hydrogenases and their accessory genes -- 6. Improvement of hydrogen production through molecular approaches and metabolic engineering -- 7. Process and culture parameters -- 8. Photobioreactors -- 9. Mathematical Modeling and Simulation of the Biohydrogen Production Processes -- 10. Scale-Up and Energy Analysis of Biohydrogen Production Processes -- 11. Biohydrogen production process economics, policy, and environmental impact.