In recent years, bacteria from genus Clostridia have attracted attention of research community because of their biofuel production capabilities. Present study reports comparative genomic (CG) analysis of 48 genomes of solventogenic and saccharolytic Clostridia. We have focused on central carbon metabolism and general stress response in the analysis. Comprehensive summaries on comparison of general genome features, COG categories, CDSs of the energy, catabolic, and sporulation pathways are given. Furthermore, we have proposed two new genome-scale metabolic (GSM) models iKK848 and iKK1425 for Clostridium pasteurianum DSM 525 = ATCC 6013 and Clostridium acetobutylicum ATCC 824, respectively. These GSM models are most comprehensive in that they account for the largest number of reactions, metabolites, and genes as compared to previous models. Model quality and metabolic flux optimization for biomass growth using iKK1425 and iKK848 are compared with previous literature. Our models had the highest quality score of 61% and 77%.