An electrochemical method of producing calcium gluconate and other salts of aldonic acids has been found, comprising the use of an aqueous alkaline bromide solution of the sugar in a diaphragm‐free cell. In place of the alkali bromide, which appears to act as a catalyst, very few other salts may be used. Alkali ferricyanide is one of these few. It was also found that salts of aldonic acids can be prepared in a diaphragm‐free and halogen‐free cell when using a mercury anode. Optimum conditions for the alkali bromide cell process carried out on a semi‐plant scale are : 1 molar sugar in a 2 per cent NaBr solution ; iron or graphite cathodes; graphite anodes; 1 to 2 amp./dm.2, 40° C., no diaphragm. Losses in bromine were minimized by changing the direction of the rectified a.c. every fifteen minutes. Costs for the manufacture of calcium gluconate from glucose are appended, together with a discussion of the commercial uses for gluconic acid and its salts.