The Present Work Deals With The Improvement Of Biohydrogen Production From Sewage Sludge. In Preliminary Studies, H2-Yield From Sludge Was Substantially Low And That Of Methane Was Significantly High. Therefore, Potential H2-Producers From Sludge Were Enriched, Characterized And Identified. H2-Producing Ability Of B. Coagulans Iit-Bt S1 On Myg Medium And Sludge Was Compared With That Of Two Established H2-Producing Strains, Enterobacter Cloacae Iit-Bt 08 And Citrobacter Freundii Iit-Bt L139. E. Cloacae Iit-Bt 08 Gave Higher H2-Yield Using Myg Medium Whereas B. Coagulans Iit-Bt S1 Showed Better H2-Producing Ability From Sludge. Heat Treatment Was Found To Be Most Effective With Regard To Reducing Microbial Load, Inhibiting Methane Production, Enhancing H2 Production And Solubilizing Sludge Nutrients Than The Other Treatments Of Sludge. Molecular Studies Using Dgge Showed That B. Coagulans Was Able To Withstand Most Pretreatments Of Sludge. Constructed Microbial Consortium Consisting E. Cloacae Iit-Bt 08, C. Freundii Iit-Bt L139 And B. Coagulans Iit-Bt S1 Was Found To Give 20 Fold Improvement Of H2-Yield Compared To That Obtained From Untreated Sewage Sludge. Besides H2 Production, These Strains Were Also Found To Possess Diverse Substrate Degrading Abilities. The Maximum H2-Yield From Synthetic Medium And Sludge, Using Consortium Was Found To Be 16.07 Mmol H2/G Codreduced And 1.75 Mmol H2/G Codreduced Respectively. Microbial Consortium In 1:1:1 Ratio Was Found Most Suitable For H2 Production. The Suitable Ph, Temperature, Sludge Dilution And Inoculum Size For H2 Production Were Found To Be 7, 37 ºC, 15 %V/V And 12 %V/V Respectively. 0.5 %W/V Glucose Supplementation Was Found To Improve H2 Production. E. Cloacae Iit-Bt 08 Dominated In The Consortium When Myg Was Used As Substrate Whereas B. Coagulans Iit-Bt S1 Was The Dominant Member In Case Of Sludge. The Bioprocess Was Successfully Scaled-Up To 20 L Continuous System. H2 Production Rate Was Observed To Increase With Increase Of Olr Up To 30 G Cod/L/H. The H2 Yield Reached 45.4 Ml H2/G Codremoved At An Olr Of 30 G Cod/L/H, Which Was Higher Than The Reported Values. The Gaseous Energy Recovery As H2 From The Substrate Was Found To Be 18.36 %. Keywords: Biohydrogen, Microbial Consortium, Sewage Sludge, Pretreatment, H2 Yield.