A pure bacterial culture utilizing chromates and bichromates as oxygen donors during growth on organic substances in anaerobic conditions was isolated from active ooze of sewage and industrial wastes containing a weak solution of chromates. A medium for growth of the bacterium was selected, and its morphological and cultural properties were studied. Chromates and bichromates are reduced only in anaerobic conditions by the bacterium or active ooze containing it, the hexavalent chromium becoming trivalent. The culture does not belong to any known species and has been therefore classed as Pseudomonas dechromaticans.