Potassium acetate is currently made by reacting petroleum-based acetic acid with potassium hydroxide. An alternate process, anaerobic fermentation of dextrose with Clostridium thermoaceticum, could be used and could possibly be cheaper. Growth characteristics and productivity of the fermentation were optimized to maximize acetate concentration in the broth. The effects of pH, type, and concentrations of nutrients and reducing agents were also evaluated. Corn steep liquor and stillage from an ethanol plant were effective and much cheaper substitutes for yeast extract. Preconcentrating the cells by ultrafiltration improved productivity, resulting in an acetic acid concentration of 53.6 g/L in 50 h at pH 6.5 using corn steep liquor. Sodium sulfide could be substituted for cysteine as the reducing agent with yields greater than 0.9 g acetic acid/g glucose.