A number of equilibrium isotherm models can be utilized for correlating experimental equilibrium results. Seven different isotherm models are studied using equilibrium data of methane, ethane and propane in activated carbon. Besides comparing the goodness of data fit, the limiting behaviors as well as the pressure and temperature derivatives of the equilibrium isotherm models are also investigated. Performance of multicomponent extensions of these isotherm models and their combinations with the ideal adsorbed solution theory are also compared with experimental data. This systematic evaluation of the more important equilibrium isotherm models provides the general basis for making a preliminary selection of an effective model for a given application. Although an accurate and thermodynamically consistent model is desirable, these requirements may often be compromised for computational simplicity in dynamic process modeling studies.