We present a detailed comparison between experimental adsorption measurements and the excess adsorption predicted by the Ono-Kondo equations. The study was done for high-pressure adsorption of methane above the critical point on microporous adsorbents. The experimental adsorption isotherms of CH4 on the activated carbon CNS-201 as well as others are compared with theory over the temperature range 243-333 K and for pressures up to 16 MPa. Extension of the model to zeolites is also discussed.