Abstract: A process for producing 2,3-dimercaptopropane-1-sulfonic acid or its salts useful as an antidote to toxic metal salt poisoning comprising reacting an allyl bromide with sodium sulfite in aqueous medium at a temperature from 50 to 100 degrees C. to produce sodium-2-propene-1-sulfonate, brominating the 2-propene-1-sulfonate, eliminating excess bromine by adding sodium sulfite, adjusting the Ph to 4.5 with sodium hydroxide, reacting the brominated compound with sodium hydrogen sulfide in an alkaline medium to produce sodium-2,3-dimercaptopropane-1-sulfonate, precipitating the raw product as a lead salt or mercury, cadmium, tin, copper, nickel, cobalt or zinc complex, suspending the precipitated product in methanol and reacting it with gaseous hydrogen sulfide, adjusting the Ph of the solution with a solid bicarbonate selected from the group consisting of sodium bicarbonate, ammonium bicarbonate and potassium bicarbonate to a Ph of 4.