A specific and adaptive 2-keto-D-gluconokinase has been isolated from cells of Leuconostoc mesenteroides grown on 2-keto-D-gluconate. The enzyme, purified 138-fold, has an optimum pH of 7.7, is most stable between pH 6.0 and 8.0, and is quickly inactivated at temperatures above 40 °C. Magnesium chloride is required for activity. ATP, ITP, and GTP served as phosphate donors but ADP and UTP were inactive. Whereas EDTA and glycine stabilized the enzyme, p-chloromercuribenzoate, hydroxylamine, copper acetate, mercury acetate, and sodium fluoride were inhibitory. The product of the enzymatic reaction was isolated and characterized as 2-keto-6-phospho-D-gluconate.