The anaerobic, photosynthetic bacterium Chlorobium thiosulfatophilum is able to convert H{sub 2}S and COS in synthesis gas to elemental sulfur. The bacterium grows on CO{sub 2} as its carbon source at 30{degrees}C. In the absence of sulfide, the formed elemental sulfur is converted to sulfate. Thus, bioreactor designs must incorporate sulfur removal as an integral part of the bioprocess. In this initial study, C. thiosulfatophilum was used to convert H{sub 2}S to elemental sulfur in a continuous stirred tank reactor with continuous gas and liquid feed. Sulfur removal was not part of this initial system design, but will be an added feature in future work. The gas used in this study contained 2.52 percent H{sub 2}S, 10.00 percent CO{sub 2}, 14.99 percent CH{sub 4} and 72.49 percent He. The liquid flow rate to the 1380 mL reactor volume ranged from 10.8--23.6 mL/min and was a variable in the study. The initial gas flow rate was 11.6 standard mL/min, although it was also changed twice during the study. The temperature was maintained at 31{degrees}C and the agitation rate was held at 200 rpm in the Bioflo reactor. Cell density was monitored by the chlorophyl method and gas composition was monitored by gas-solid chromatography. Light at 2200 lux was supplied using two 40W tungsten light bulbs on the outside of the glass reactor vessel.