The ternary system CO2-limonene-citral was chosen as a model system in order to study the extraction of terpenes from lemon oil using supercritical carbon dioxide. Extractions were performed at several pressures and temperatures to evaluate the influence of these parameters on the separation efficiency. Extract composition was monitored by capillary gas chromatography. A theoretical model, based on a modified Peng-Robinson equation of state, was used to simulate the thermodynamic and mass transfer aspects of the extraction column. The critical parameters and the acentric factors of limonene and citral were estimated by group contribution methods. The method developed by Abdoul et al., which allows the calculation of binary interaction parameters (k(ij)), was applied to terpenic compounds. The extraction experiments were simulated using this model, and the extraction profiles were accurately reproduced.