Henry′ s law constants for acetone, 2-butanone, 2,3-butanedione, and isobutyraldehyde were investigated using a horizontal flow reactor coupled to a molecular beam mass spectrometer. These organics belong to a class of oxygenated compounds that are increasingly used as industrial solvents and were chosen to better understand and evaluate their atmospheric fate. All experiments were performed at atmospheric pressure and temperature over the range of (275 to 298) K. The Henry′ s law constants H-x at T = 298 K are the following (in units of M-atm(-1)): acetone, (26 ± 6); 2-butanone, (2.7 ± 0.3); 2,3-butanedione, (57 ± 8); and isobutyraldehyde, (0.60 ± 0.10). The -d In H-x/d(1/T) values are the following (in units of K): acetone, (6400 ± 1600); 2-butanone, (12 000 ± 5000); 2,3-butanedione, (6700 2400); and isobutyraldehyde, (4500 ± 2900). The uncertainties listed above are ± 2σ and have been calculated using a propagation of errors analysis.