The aim of this work is to provide new experimental data of the adsorption equilibria of CH4/CO2 binary mixtures on a microporous activated carbon Ecosorb. The mixtures studied were made for two nominal feed-gas compositions of 25 and 75 mol %. Adsorption isotherms were performed using a homemade manometric technique, combined with gas chromatographic analysis of the equilibrium gas-phase composition. Experimental isotherms are provided up to 3 MPa for three temperatures at 303.15 K, 323.15 K, and 353.15 K. The equimolar mixture was previously studied thus allowing a description of the CO2/CH4 mixture adsorption in a full range of pressure, temperature, and composition. As expected, the binary adsorption isotherms mixture reveals a preferential adsorption of CO2 compared to CH4 over the whole pressure and temperature range. Additionally, these adsorption data were used to check the capability of the ideal adsorbed solution (IAS) theory to estimate the mixture adsorption of CH4/CO2. At low pressures (up to 1.5 (MPa)) the IAS model is in good agreement with the experimental data.