In this study, the essential oil of aerial parts species of a plant called Spearmint was extracted by CO2 to optimize the results of the supercritical extraction process. In order to achieve maximum total yield extraction and SF-CO2 concentration, tests were done in a laboratorial pilot considering the Taguchi method under following condition: pressure. 90,100,140,170 bar, temperature. of 35, 40, 45, 50 degrees C, mean particles size: 250,500,710,1000 mu m, flow rate 1,3,5,8 ml/s and dynamic time 30,50,90,120 min. The optimizing conditions for SCE and SF-CO2 concentration are: 90 bar, 45 degrees C. 500 mu m. 5 ml/s, 120 min and 90 bar, 35 degrees C, 250 mu m, 1 ml/s, 30 min. SCE total yield and CO2 concentration are 2.032% and 0.033 mg/ml. In similar and optimal conditions of extraction, supplementary tests were done so resulted and experimental amount of the calculated sum are in accordance with total yield extraction and SF-CO2 concentration. This is the first report announcing optimization of spearmint SCE by use of Taguchi method. (C) 2012 Elsevier By. All rights reserved.