An environmentally benign method for the mineralization of sulfur mustard has been proposed involving chemical hydrolysis of sulfur mustard to thiodiglycol, and then the biological degradation of thiodiglycol to generate biomass and gaseous carbon dioxide. Alcaligenes xylosoxidans (SH91) was isolated based on its ability to utilize thiodiglycol as a sole carbon source. This article compares different biological reactor designs and experimentally assesses their relative effectiveness in degrading thiodiglycol using pure cultures of SH91. The reactor configurations studied are batch, continuous stirred-tank reactor (CSTR), and CSTR with cell recycle. From the results, it is clear that the CSTR with cell recycle offers superior performance for a given residence time or volume. These pure culture data are necessary for accurate design of a pilot-scale system where mixed cultures will be employed because of a possible incomplete chemical hydrolysis step.