The influence of aeration level, initial pH, initial cell concentration, and fermentation time on the xylitol production from rice straw hemicellulose hydrolysate by Candida mogii was studied. A multifactorial experimental design was adopted to evaluate this influence. A statistical analysis of the results showed that the aeration level and the initial pH had significant effects on yield factor, volumetric productivity, and xylose consumption. For the latter, fermentation time was also a significant variable. Based on the response surface methodology, models for the range investigated were proposed. The maximum values for the yield factor (Y-p/s) and volumetric productivity (Q(p)) were, respectively, 0.71 g/g and 0.46 g(Lh).