The invention provides a method for preparing a carboxylic acid, which method includes the steps of providing magnesium carboxylate, wherein the carboxylic acid corresponding with the carboxylate has a solubility in water at 20° C. of 80 g/100 g water or less; acidifying the magnesium carboxylate with HCl, thereby obtaining a solution comprising carboxylic acid and magnesium chloride (MgCl2); optionally a concentration step, wherein the solution comprising carboxylic acid and MgCl2 is concentrated; precipitating the carboxylic acid from the solution comprising the carboxylic acid and MgCl2, thereby obtaining a carboxylic acid precipitate and a MgCl2 solution.