Background Xylitol is an important commercial sweetener that can be produced by fermentation. Previous studies of xylitol production have not been able to combine a high final product concentration, and a high average productivity and yield, in a single process. Results High-cell density cultures of the yeast Candida magnoliae TISTR 5663 were used to produce xylitol by repeated fed-batch fermentations under oxygen limiting conditions involving feeding of xylose and nitrogen. Xylitol yields of 0.727, 0.719 and 0.720 g g1 were obtained at average biomass concentrations of 21, 48, and 50 g L1, respectively, using an initial xylose concentration of approximate to 60 g L1 under controlled conditions (agitation rate 300 rpm, aeration rate 1.0 vvm, pH 7.0, 30 degrees C). For a total duration of 750 h of a repeated fed-batch fermentation, an average xylitol productivity of 1.149 g L1 h1 was attained within the fed-batch periods. The final xylitol concentration was in the range 235284 g L1 depending on the stage of feeding. Conclusion The fed-batch xylitol production developed in this work combined high final product concentration, xylitol productivity and yield in a single process.(c) 2012 Society of Chemical Industry