We studied the thermodynamics of benzene adsorption on a series of oxidized closed-ended multiwalled carbon nanotubes at 298 K. Combined experimental and simulation results showed the significant effect of the surface heterogeneity on the benzene adsorption enthalpy and entropy at low surface coverages. For oxidized carbon nanotubes and low benzene uptakes, the differential entropy of the adsorbed phase is close to the differential entropy of solid benzene. Therefore, benzene molecules interacting with surface heterogeneities are ordered in quasi-solid structures at 298 K. At higher surface coverages, the ordering and packing of benzene molecules is liquid-like. (C) 2012 Elsevier B.V. All rights reserved.