The Henry’s law constant is required to size absorption processes. However, its experimental determination for multi-component gases in presence of complex liquids remains problematic in the process industry and research field. This work presents a new experimental setup built to measure Henry’s law constants easily. The apparatus brings gas and liquid phases into contact before and after equilibrium in medium pressure conditions (from 1 to 10 bars). Thanks to standard sensors, temperature, pressure and phase concentrations of the components are recorded continuously, permitting to calculate the Henry’s law constant. Three types of water were tested and put in contact with a real biogas mix. Henry’s law constants for carbon dioxide and methane were obtained with good accuracy and were consistent with the values reported in the literature for tap water. Results obtained with the apparatus show that values of Henry’s law constant can differ between tap water and recycled water. Carbon dioxide absorption is strongly reduced when recycled water is used. We can conclude that the proposed apparatus is a convenient experimental set up for determining Henry’s law constants with good accuracy and as it is movable it can be helpful for engineer in charge of biogas upgrading system.