Abstract:The selective inhibition mechanisms of various pretreatment methods like heat-,acid-,alkali-,chemical inhibitor-,aerate-,as well as the load shock pretreatment are reviewed and their corresponding bio-hydrogen performance are compared and discussed.The disagreement in optimal pretreatment methods should be attributable to the difference in the tested seed sludge,kinds and concentration of substrate,temperature,pH and reactor type.In addition,pure substrates of glucose or sucrose are currently used as substrate for hydrogen production in many studies.Practical organic wastes are recommended to be used as substrate for comparison of the effectiveness of different pretreatment methods.