We have measured the infinite dilution activity coefficients for five volatile organic compounds (dichloromethane, chloroform, 1,2-dichloroethane, trichloroethylene and benzene) in aqueous salt solutions over the temperature range of 10 degrees C to 40 degrees C, and sodium chloride concentrations from 0 to 2.5 M using headspace gas chromatography. These data were easily fit as a function of salt concentration using the Setschenow expression, and as a function of temperature. By taking derivatives of the fitted data as a function of temperature, one obtains estimates of the partial molar excess enthalpy and entropy at infinite dilution of the organic chemicals as a function of temperature and salt concentration.