AbstractA laboratory installation was developed for continuous cultivation of hydrogen bacteria by turbidistate with a capacity of about 5 1. A steady state process withHydrogenomonas eutrophawas realized which produces up to 40 g/1 · day of dry biomass. Optimum concentration values for oxygen, hydrogen, carbon dioxide in the gas phase for various densities of bacterial suspensions were found. The minimum concentrations of bioelements are: N 50–70 mg/1, P, Mg, K 20–40 mg/1.The biomass of hydrogen bacteria is characterized by a high protein content (up to 77%) including irreplaceable amino acids up to 40%, and nucleic acids up to 10%. Oxygen and nitrogen deficiency lead to a protein decrease up to 46% and an increase in the concentration of poly‐β‐hydroxybutyric acid. The possibility of a continuous unsterile cultivation ofHydrogenomonaswith prevalence over the growth of the accompanying microflora