The interfacial tension (γ) was measured at 25°C at the xylene-water interface in the presence of various concentrations (C) of fluorocarbon, hydrocarbon surfactants and their mixtures. From the γ-log C curves the c.m.c., saturation adsorptionT and area/molecule have been established. The results obtained show that contrary to the case for the air/water Interface, fluoro-carbon surfactants do not show more adsorption at the xylene-water interface, when compared with their hydrocarbon counterparts. Moreover, mixtures of fluorocarbon and hydrocarbon surfactants did not show any preferential adsorption of the fluorocarbon surfactant molecules. The rate of coalescence of xylene/water emulsions was measured at 25°C by droplet counting as a function of time. The rate constant of coalescence was calculated from the slope of the tangent of the log Ntversus t curves. The results showed that neither fluorocarbon surfactants, nor their mixtures with hydrocarbon surfactants gave significantly more stable xylene in water emulsions, when compared with those prepared using the hydrocarban surfactants. This was attributed to the fact that neither fluorocarbon surfactants.nor their mixtures with hydrocarbon surfactants lowered the interfacial tension t o a greater extent than the hydrocarbon surfartants, nor did they form more coherent films. The lack of strong adsorption of fluorocarbon surfactant molecules at the xylene-water interface probably stems from the weak mutual solubility of perfluoroalkane and xylene.