Determinative studies were carried out with an obligatory anaerobic spore-forming sulfate-reducing bacterium, strain No. 64, isolated from the SKARVS NES district in the East Antarctica. This sulfate-reducing bacterium belongs to the genus Desulfotomaculum differing from all of the known species of the genus in respect to glucose fermentation, gelatin liquefaction, optimum temperature for growth, and nutritional requirements. The strain was determined to be a new species of the genus Desulfotomaculum, D. antarcticum, IIZUKA et OKAZAKI nov. sp.