This work is focused on the investigation of the phase behavior of binary systems formed by castor oil in compressed propane and n-butane. The experiments were conducted in a high-pressure variable-volume view cell in the temperature range of 30-150 degrees C, for solvent overall composition ranging from 15 to 99 wt.% and pressures up to 240 bar. Results indicate the existence of a complex phase behavior for both systems investigated, with liquid-liquid, vapor-liquid and vapor-liquid-liquid phase transitions. The liquid-liquid phase transition presents upper and lower critical solution temperatures. (c) 2004 Elsevier B.V. All rights reserved.