Thermoanaerobacterium thermosaccharolyticum shows promise as a host for n-butanol production since it natively has the required genes involved in the n-butanol biosynthetic pathway. Overexpression of the natively occurring bcs operon containing the genes thl, hbd, crt, bcd, etfA, and etfB responsible for the formation of butyryl CoA increased the n-butanol production by 180% compared to the wild type from a n-butanol titer of 1.8 mM to 5.1 mM. The deletion of one of the six alcohol dehydrogenase genes confirmed that it was the primary gene responsible for ethanol and n-butanol production from acetyl CoA and butyryl CoA respectively.