Abstract The purpose of this study was to quantitate the transport behavior of several organic solutes in matrix systems composed of micron-size hexadecane droplets dispersed in an aqueous gelatin gel where the oil-water interfacial barrier to transport was expected to play an important role. Two interrelated experiments were conducted. The first was the one-dimensional aqueous uptake of the solute by the matrix which was a continuous layer placed at the bottom of a beaker. The other experiment was solute uptake and release from aggregates of oil droplets suspended in an aqueous medium. Solutes investigated were 14 C-labeled cholesterol, diethylphthalate, 14 C-labeled octanol, and 14 C-labeled progesterone. The data have been analyzed by various physical models. It was found that cholesterol transport essentially was controlled by the oil-water interfacial barrier in both kinds of experiments—even when the matrix thickness was as large as 3.7 mm. For the other solutes, the oil-water interfacial barriers were found to be controlling in the experiments with aggregates (10-1000 μ). However, in the experiments with the continuous matrix layers, bulk matrix diffusion factors as well as the oil-water interphase transport were found to be important for these solutes. The techniques developed in this investigation should be useful: ( a ) in the quantitation of interfacial barriers in oil-water interphase transport of solutes, and ( b ) in the separation of various bulk diffusional resistances from interfacial resistances in complex multiphase matrices.