Applicable to products having CO2 contents of more than 0.01 % (m/m). Three cases are envisaged. The product containing neither sulphides nor chlorates or containing sulphides or chlorates. The principle in presence of neither sulphides nor chlorates consists in liberation of carbon dioxide in a flow of gas and absorption in an excess of standard volumetric barium hydroxide solution. Titration of the excess with standard volumetric hydrochloric acid solution in the presence of thymolphthalein as indicator. In presence of sulphides, pretreatment by oxidation of the sulphides by hydrogen peroxide and boiling, in presence of chlorates, pretreatment by reduction of the chlorates to chlorides by the addition of iron(II) sulphate.