A new model is proposed to a priori predict single component adsorption equilibria of different gases and vapours on activated carbons and graphite/graphitized carbon black. Emphasis is laid on the Henry region, where the interaction energy between adsorbate molecules and the adsorbent determines adsorption characteristics. II is shown that Henry coefficients can be predicted on the basis of the three-dimensional van-der-Waals equation for gases and the Hamaker constant of solid, which is different for activated carbon or graphite/graphitized carbon black, respectively. The quality of prediction is superior to the Steele/Lennard-Jones model in the case of graphite/graphitized carbon black, and yields a priori results for activated carbon without any adjustment.