Differential ebulliometry and non-steady-state gas-liquid chromatography have been used to measure activity coefficients at infinite dilution for 31 binary systems containing alkanes, ketones, and alcohols over the temperature range 303-343 K. A comparisonbetween the results obtained with these two methods shows that differential ebulliometry provides more reliable results for the systems with a relative volatility lower than 15. Non-steady-state gas-liquid chromatography can however readily be used as an alternative to conventional gas-liquid chromatography for the measurement of activity coefficients at infinite dilution in low-boiling solvents.