In this study, fermentation tests on different initial glucose concentrations, ranging from 100 to 200 g/L, were conducted to identify the ethanol tolerance of Kluyveromyces marxianus EMS-26 strain at 42 degrees C. Lipid and nutrient additions to the fermentation medium were made in order to improve the ethanol production at 42 degrees C. The results obtained showed that the addition of unsaturated fatty acids and sterols to the SSF media reduced hydrolysis yields and ethanol production as compared to tests carried out on controls without lipid supplementation. These results seem to indicate that cellulases performed better when no lipid supplementation was used. The decrease in the saccharification in the presence of 0.5% Tween 80 (10% decrease in the filter paper activity) seems to be closely related to the denaturation of cellulase complex rather than lipids interference with cellulase binding.