This work reports some experimental data on the adsorption of methyl tert-butyl ether (MTBE) and of 1-methylbutane vapors onto commercial activated carbon. 1-Methylbutane is assumed to simulate hydrocarbons present in vapor emissions from gasoline car tanks. Equilibrium adsorption data for MTBE + air and 1-methylbutane + air systems have been obtained from breakthrough curves and have been correlated by means of the Langmuir isotherm. Furthermore, the pseudoternary system MTBE + 1-methylbutane + air has been studied and the experimental competitive equilibrium data have been successfully compared with those obtained by ideal adsorbed solution theory. Experiments give information also on the kinetics of the adsorption operation. Modeling breakthrough curves allow the value of an overall mass transfer coefficient to be evaluated.