The solubility and diffusion coefficient of oxygen and carbon dioxide were measured in both the pure and emulsified of two fluorocarbons, perfluorotributylamine and perfluorobutyl perfluorotetrahydrofuran. The solubility coefficient and the diffusivity of oxygen in the pure form of the fluorocarbons decreased with decreasing partial pressure of Oxygen ( {Mathematical expression}), but the solubility coefficient and the diffusivity of carbon dioxide were independent of its partial pressure. The solubility and diffusion of oxygen in the emulsified form of the fluorocarbons followed the pattern expected from the behavior of oxygen in the pure fluorocarbon. The experimental results suggest that there exists a physical and/or chemical interaction between oxygen and the fluorocarbons, and this interaction is more pronounced at partial pressures below 150 mm Hg. Comparisons of the oxygen content in the fluorocarbon emulsions with that in whole blood show that at {Mathematical expression} of 760 mm Hg, the oxygen content in the fluorocarbon emulsions is approximately one-half that in whole blood, but at {Mathematical expression} of 50-150 mm Hg, the oxygen content in the emulsions decreases to values which are less than one-tenth that of whole blood. © 1977 Springer-Verlag.