This paper presents experimental excess adsorption isotherms of N-2, CH4, and C3H8 on activated carbon (F30/470 from Chemviron Carbon) at five different temperatures (303 K, 323 K, 343 K, 363 K, and 383 K). The whole pressure range is covered for subcritical conditions and the maximum pressure is 10 MPa for supercritical conditions. The adsorption device is a magnetic suspension balance which has been instrumented and automated for adsorption measurements in the range of high temperatures and high pressures (303 K to 423 K, 0 to 10 MPa). The coherence of the results is checked by comparing the N2 data at 303 K to those obtained by a classical volumetric apparatus. Discrepancies appear to be less than 3.5%. The influence of the buoyancy effect on the results is discussed.