The efficiency of active packaging films is strongly dependent on the vapour sorption behaviour of the plastic material and of the active substance (scavenger). In oxygen scavenging films the diffusion and solubility of oxygen is influenced by the moisture; in addition, the scavenger material is triggered or activated by moisture. Therefore, the sorption behaviour of plastic material is of great importance for active films. In contrary to food, there is no collection of vapour sorption isotherms for plastic films.By means of dynamic vapour sorption DVS the sorption isotherms of plastic films, coats of lacquers, compounds and active materials shall be measured. Where possible, the data shall be compared with the efficiency of active packaging films. Aim is to receive more information of the working mechanisms of active packaging films.