Abstract: The present invention relates to a method for purifying naproxcinod comprising the steps of: a) dissolving or dispersing a mixture containing naproxcinod in an amount higher than 90% by weight in a solvent; b) cooling the solution or two phases dispersion under stirring to a temperature ranging from ?20° C. to 10° C. c) optionally seeding the solution with crystals of naproxcinod d) stirring, by maintaining the temperature in the range from ?40° C. to 10° C. e) collecting the formed solid by maintaining the temperature under 15° C. A further object of the invention is a crystalline form of naproxcinod.