In addition to the ecological and evolutionary interest, hyperthermophile organisms are rapidly identified as potential sources of stable biomolecules having potential application in industrial processes. An understanding of their growth characteristics and metabolism is necessary to realize their full biotechnological potential. A major limitation to their study has frequently been the small amount of biomass that can be generated. Within the archaeal hyperthermophiles, some species are extensively studied: (1) thermoacidophilic species belonging to the order Sulfolobales (2) methanogens and (3) a number of species belonging to the order Thermococcales. The chapter discusses the cultivation of sulphur-reducing hyperthermophiles in bioreactors. Pressurized bioreactors have been developed in consideration that high pressure may be important for the growth of deep sea sulphur-reducing hyperthermophiles. Simpler and less expensive approaches for the cultivation of hyperthermophiles are also discussed.