Rohrschnelder determined the partition coefficients of six prototypical solutes In a wide variety of solvents of interest for chromatographic, polymeric, and general chemical purposes. His data set, due primarily to its scope, has been used as a “benchmark” against which many models of solution behavior have been tested. As the accuracies of various models and correlations have improved, experimental errors in excess of 15% have been Inferred. The present study Is devoted to the experimental measurement of many of the solute-solvent pairs examined by Rohrschnelder and a limited number of additional solvents. An improved methodology which we believe Is substantially more accurate (better than 5% in general) and precise (2% at worst) Is employed.