Quantitative structure–property relationships for predicting the water–octanol partition coefficient, logPOW, are reported. The models are based on local properties calculated at the standard isodensity surface using semiempirical molecular orbital theory and use descriptors obtained as the areas of the surface found in each bin in a predefined binning scheme. The effect of conformation is taken into account but was found to have little effect on the predictive power of the models. A detailed error analysis suggests that the accuracy of the models is limited by that of the experimental data and that the best possible performance is approximately ±0.5 log units. The models yield a local hydrophobicity function at the surface of the molecules.