Corn stover, contains 70% cellulose + hemicellulose and 15-20% lignin. The hemicellulose can be converted to monomeric and oligomeric sugars by hydrolysis, to form a xylose-enriched liquid hydrolysate fraction that can be used for xylitol production. Xylitol has many interesting applications in the food, pharmaceutical, and odontological industries. Pichia stipitis FPL-YS30 (xyl3) is a D-xylulokinase mutant that converts xylose mainly into xylitol. This yeast was cultivated in corn stover hemicellulosic hydrolysate, which was obtained by vapor phase diethyloxalate (DEO) pretreatment. This work evaluated supplementation of corn stover hemicellulosic hydrolysate (CSHH) obtained by DEO pretreatment to improve xylitol production by P. stipitis FPL-YS30. The hydrolysate pH was increased to 5.5 with Ca(OH)₂ before sterilization by membrane filtration. Different media used urea, yeast extract, phosphates and magnesium salts. Experiments were carried out in 125 mL Erlenmeyer flasks containing 50 mL of medium and inoculum (1.0 g/L) on a rotary shaker at 200 rpm, 30°C.  Addition of phosphates and magnesium salts favored the specific cell growth, xylose consumption and xylitol production rates by P. stipitis FPL-YS30. The maximum xylitol yield (0.766 g_xylitol/g_xylose) was obtained in medium containing urea, yeast extract, phosphates and magnesium salts. The L-arabinose was totally or partially (17%) consumed depending on the presence or absence of salts, respectively. In general, the acetic acid was consumed concomitantly with the xylose. The untreated CSHH obtained by DEO pretreatment contains low acetic acid and phenolic compounds. Its supplementation by adding phosphates and magnesium salts improved xylitol production by P. stipitis FPL-YS30.