D-xylose was bioconverted into ethanol using yeast of Pichia stipitis CBS 5773. A similar effect of the oxygen transfer coefficient, K(L)a, on the ethanol yield was observed among various configurations of bioreactors, namely, shake flask (250 ml, 500 ml), spinner flask (500 ml), and stirred tank (5 L). That is, the ethanol yield could reach about 0.37 g ethanol/g xylose if K(L)a was lower than 0.004 sec(-1). It was noted that the yield fell rapidly as K(L)a increased, however, high aeration rate promotes cell growth rate. Also, the technique of strain adaptation and selection was used successfully to enable the yeast to ferment the newspaper hydrolzyates. Again, the effect on the yield due to K(L)a in both synthetic and hydrolzyate media was quite consistent.