This study deals with the modeling of the extraction of solid lanoline from raw wool under near-critical conditions using 5% ethanol in CO2, using our previous experimental data. A mass-transfer model is developed to explain the extraction results at T = 30 degrees C, below the melting point of lanoline (36-42 degrees C). Two variables are studied, the extraction pressure and the solvent mass flowrate. Our model depends on three parameters: the solubilities of the two lanoline fractions and the lanoline mass transfer coefficient. The model is a set of first order partial differential equations, that is solved by orthogonal collocation in combination of optimization of the parameters. The fluid-side mass-transfer coefficient decreases with extraction pressure and is about 5 x 10(-6) m/s for Re < 1 (at 70-150 bar) and depends on fluid velocity. The solubilities of lanoline fractions, independent of flowrate, agree very well with those previously reported.