Dimensionless Henry's law constants k H (air-water partition coefficients) for a series of aromatic aldehydes and ketones were measured by using an internal standard method. It was demonstrated that the technique works well for both liquid and solid species. The k H values of these compounds, which usually are difficult to be determined experimentally, are in the order of 10 -6 to 10 -3 . The measurements were carried out under atmospheric pressure and at various temperatures [(273 to 298) K]. The temperature dependence of k H was also studied, and the van't Hoff parameters were calculated. All the data are reported with the corresponding standard deviations and uncertainties at the 95 % confidence level. The theoretical dipole moments in the gas phase were computed by utilizing Cerius 2 molecular modeling software to justify the discrepancies among the k H values of the isomers. These calculations exhibit linear relationships between the dipole moment and k H within each isomer series.