Synopsis The phase diagram of system polyoxyethylene 10 stearyl ether (Steareth 10)/geraniol/olive oil/H(2)O was determined using visual observation and low angle X-ray diffraction. The system formed two isotropic solution phases: water and a geraniol solution of Steareth 10 and water. In addition a lamellar liquid crystal was formed along the water-Steareth 10 axis. It solubilized geraniol and olive oil in different locations within its structure with maximum solubilization depending on the site. Geraniol is only solubilized in the hydrocarbon chain part of the bilayer, while olive oil is solubilized both at that site and between the terminal methyl group layers. The results provided essential information about the behaviour of geraniol during evaporation.