Infinite dilution activity coefficients and Henry’s law coefficients have been measured for 11 halogenated C-1 to C-3 compounds in 1-octanol above room temperature using a gas-liquid chromatographic measurement method. Then, using our earlier data for these substances in water and a correlation relating the limiting activity coefficients of a substance in pure water and in pure 1-octanol to their octanol/water partition coefficients, these latter quantities have been computed. One conclusion from these measurements is that the limiting activity coefficients in octanol and the octanol/water partition coefficients of the halogenated compounds studied are only weakly dependent on temperature over the range from 25 to 50 degrees C. Also, from these and our earlier data, we have estimated the infinite dilution partial molar excess enthalpies and excess entropies of these compounds in both 1-octanol and water.