Abstract: An arrangement for measuring the carbonation level of a liquid, useful for controlling the extent of carbonation of a beverage, particularly in a continuous process stream. A portion of the process stream is diverted to flow adjacent to a gas permeable membrane having a diluent gas such as helium or nitrogen flowing on the opposite side thereof. The diluent gas stream absorbs carbon dioxide in proportion to the extent of carbonation of the beverage, and a suitable characteristic, such as thermal conductivity or infrared absorption, of the diluent gas and carbon dioxide mixture is then measured as an indication of the carbonation level of the beverage.