A low pressure vapor-liquid equilibrium apparatus has been developed, tested and verified for the measurements of dilute solution activity coefficients for different organic solutes in aqueous systems. Activity coefficient data were measured for aqueous binary mixtures involving methanol, acetone, and benzene at 25 degrees C. The experimental measurements targeted the range of solute liquid compositions extending from the Gas Chromatograph detection limit to 0.3 mole fraction for methanol and acetone, and to the miscibility mole fraction for benzene. Precise extrapolation to determine the infinite dilution activity coefficients (gamma(i)(infinity)) was achieved. Instrumental, external and internal consistency tests performed on the acquired data indicate a good level of experimental consistency.