The water-R134a partition coefficients for a set of 11 organic solutes have been measured using a high-pressure, spectroscopic technique. Water partition coefficients of the organic solutes were measured in the gas and supercritical phases of R134a. A linear solvation energy relationship (LSER) was developed to predict the measured water-R134a partition coefficients using the Kamlet-Taft descriptors of the solute and solvent molecules as independent variables. Considering the entire water-R134a partition coefficient data, the LSER model has an average absolute relative deviation of 30%. Only considering the data above the critical density of R134a, the LSER has an average absolute relative deviation of 17.5%.