This study applied inverse gas chromatography (IGC) to examine the surface properties of an untreated alumina and alumina treated with four types of silane coupling agents. The carbon content of the silane coupling agents adsorbed on the surfaces of the alumina was analyzed to examine the number of adsorption layer. The results suggested that multilayers are generally adsorbed onto the alumina surfaces based on the assumption that a molecule of each silane coupling agent occupies an area of 0.5-1 nm(2). This paper presents and discusses the dispersive properties expressed by gamma(D)(S), which is the dispersive component of the surface free energy, as determined at various temperatures. The gamma(D)(S) values of the alumina treated with gamma-methacryloxy propyl trimethoxy silane (MTMS) were the highest, while those of the alumina treated with gamma-amino propyl triethoxy silane (AES) were the lowest at the same measuring temperature. The alumina treated with gamma-glycidoxy propyl trimethoxy silane (GMS) and gamma-mercapto propyl trimethoxy silane (MCMS) showed gamma(D)(S) values in close agreement to those of most resins (approximately 30 mJ m(-2) at 160 degrees C. (C) 2008 Elsevier B.V. All rights reserved.