Xylitol production by K. marxianus CCA510 was greater in CABH-2 medium (concentrated but not detoxified or supplemented),reaching 12.73 g L−1. However, in the CABH-4 medium, which was treated with the charcoal of smaller particle size, the xylitol concentration was 12.29 g L−1. In CABH-1, which had not been concentrated, xylitol concentration was 6.76 g L−1. However, analyzing the productivity of xylitol (YP/S), which is calculated taking into account the initial amount of xylose present in the medium fermentation, it is noticed that in CABH-1 (YP/S= 0.36 g g−1), this value was higher than in the CAB-4 (YP/S= 0.34 g g−1), i.e. for K. marxianus CCA510, the concentration and the treatment of the hydrolysate with activated charcoal showed no relevant improvement in xylitol production (Table 2). It is highlighted that in none of those media the yeast was able to produce the polyol before 24 h of the cultivation (Fig. 2). Ethanol production was also observed (24.34 g L−1 in CABH-2), which shows that the removal of interferers is not a critical parameter in the process, and the yeast probably metabolized glucose and xylose to produce ethanol. On the other hand, the lower ethanol production was observed in the medium containing the lowest amounts of glucose, CABH-1 (1.89 g L−1).