The inverse gas chromatographic method has been used to evaluate dispersive surface energies and acid/base interaction values for a styrene/maleic anhydride copolymer over a substantial temperature range. Surface energy calculations require knowledge of the dimensions of adsorbed molecules; conventional values of these for linear alkanes result in reliable surface energy data at near-ambient temperatures. Above about 60-degrees-C, however, more reliable surface energy data are obtained when the dimensions of the adsorbed species are corrected by density/temperature variations of the vapors. The copolymer studied was shown to be amphoteric, but with an appreciable prevalence of basic surface sites.