The octanol–water partition coefficient, KOW, of 2-heptenal, 2-octenal, 2-nonenal, 2-nonanone and octanal was obtained from headspace vapour concentrations in a bubble column determined by selected ion flow tube mass spectrometry (SIFT-MS) with and without addition of 1-octanol to the water solution. Experimental values for log KOW at 299 K range from 2.06 ± 0.12 (2-heptenal) to 2.31 ± 0.14 (1-octanal). Partition enthalpies, −Δ0Hw→o, of 19.9 ± 6.2 kJ mol−1 (1-octanal) up to 118.1 ± 8.5 kJ mol−1 (2-nonanone) were obtained. In conjunction to the determination of KOW, Henry's law coefficients of (2.76 ± 0.38) × 10−3 molg moll mg−3 ml3 for 2-heptenal to (2.79 ± 0.16) × 10−2 molg moll mg−3 ml3 for 1-octanal were experimentally obtained.