Supercritical carbon dioxide extraction to separate phytosterol esters from fatty acid esters and tocopherols was simulated and optimized using the group contribution equation of state. Experimental extraction data at 328 K, pressures ranging from 200 to 280 bar and solvent-to-feed ratio around 25, was employed to verify the performance of the thermodynamic model. The raw material is the product obtained after a two-step enzymatic reaction carried out oil soybean oil deodorizer distillates, and contains mainly fatty-acid ethyl esters, tocopherols and phytosterol esters. The extraction process was simulated using model substances to represent the complex multicomponent feed material. Nonlinear programming techniques were applied to find out optimal process conditions for a steady-state countercurrent process with partial reflux of the extract. The process optimization procedure predicts that a product with 94.2 wt % of phytosterol ester purity and 80% yield could be achieved. (C) 2009 American Institute of Chemical Engineers AIChE J, 55: 1023-1029, 2009