Eucalyptus hemicellulosic hydrolysate was evaluated for xylitol formation by Candida guilliermondii FTI 20037. Batch fermentation carried-out with high inoculum density (3.0 g/l) showed a dramatic improvement in substrate utilization and resulted in the formation of 13.77 g/l xylitol after 88 h. The use of a lower inoculum concentration (1.0 g/l) resulted in an initial lag phase characterized by absence of xylose consumption. Furfural, 5-hydroxymethylfurfural and acetic acid were assimilated by the yeast during the fermentation period. Copyright (C) 1996 Elsevier Science Ltd.