The adsorption data of the pure gases methane, ethylene and hydrogen on two types of zeolites and two types of activated carbon materials were measured using a volumetric method at 293 K and at pressure up to 26.8 MPa. Four different approaches were tested for description of the experimental equilibrium data. Based on the experimental data obtained by other authors at very wide range of pressure (0–650 MPa), we propose a new modeling type adsorption isotherm, describing the excess of adsorption of supercritical gases on micro porous adsorbents. The analysis was developed for the description of the phenomena minimum of adsorption isotherms at very high pressure. The concept of inflection point and its thermodynamically treatments were developed. The comparison of the different models describing adsorption isotherms allows a critical discussion of their accuracy.