A mathematical model was described and solved for extractive fermentation in a continuous stirred tank bioreactor. The effects of bioprocess parameters on the classical and the extractive ethanol fermentations using decanol as a solvent were investigated. The maximum ethanol yields in the classical and the extractive fermentations for the initial substrate concentration, 200 g/l were obtained as 7.73 g/l-h and 26.24 g/l-h, respectively. When the initial substrate concentration was increased from 100 g/l to 600 g/l, ethanol yield increased from 12.43 g/l-h to 57.23 g/l-h in the extractive fermentation. When another process parameter, i.e., solvent dilution rate, increased from 0.5 h(-1) to 5.0 h(-1), the value of total ethanol yield increased from 6.07 g/l-h to 22.63 g/l-h.