Infinite dilution activity coefficients (gamma(infinity)) have been determined by using a gas-liquid chromatography (GLC) technique for benzene, toluene, methanol, ethanol, 2-propanol, and acetaldehyde in ethylene glycol and ethylene carbonate in a range of temperatures from 50 to 110 degreesC. In the literature, there were no reported data for gamma(infinity) for any of the studied solutes in ethylene carbonate or for acetaldehyde in ethylene glycol. A few gamma(infinity) data were available for benzene, toluene, methanol, and 2-propanol in ethylene glycol, but they were limited to a low-temperature range (<70 degreesC). The measured gamma(infinity) data in this work therefore provide a good source of gamma(infinity) data in the higher temperature region.