The influence of pore size distribution of the phenol-based adsorbents (RP-15 and RP-20) on adsorption and desorption of methane was investigated. The isotherm data were measured using a static volumetric method at three different temperatures (293.15, 303.15, and 313.15) K and at pressures up to 35 atm. Experimental data were well-correlated by the Sips and Toth isotherm models. The surface energetic characteristics of the adsorbents were evaluated by using the Clausius-Clapeyron equation.