Methyl tert-butyl ether (MTBE) is the basic oxygenated motor fuel additive in Europe and is a volatile organic compound (VOC). Many studies have been devoted to identify the sources of this polluting compound in the environment, with special concern to shallow groundwater contamination. In this work, original experimental data from the adsorption of vapours mixtures of MTBE, cyclohexane and air onto commercial activated carbon are reported. Equilibrium adsorption data for MTBE+ air and cyclohexane + air systems have been obtained from breakthrough curves and have been correlated by means of the Langmuir isotherm. Furthermore, the pseudoternary system MTBE + cyclohexane + air has been studied and the experimental competitive equilibrium data have been successfully compared with those obtained from theory of adsorption for an ideal solution. The results showed that MTBE adsorption capacity of activated carbon is strongly reduced in the presence of cyclohexane. Information on the kinetics of the adsorption operation are also reported. In particular, MTBE showed a maximum excess concentration caused by the displacement of adsorbed MTBE by cyclohexane. (C) 2011 Elsevier B.V. All rights reserved.