A fungus. Fusarium verticillioides (NRRL 26518), was isolated by screening soil samples using corn fiber xylan as carbon source. The extracellular xylanase from this fungal strain was purified to apparent homogeneity from the culture supernatant by ultrafiltration using a 30,000 cut-off membrane. octyl-Sepharose chromatography and Bio gel A-0.5 in gel filtration. The purified xylanase (specific activity 492 U/mg protein: MW 24,000. pI 8.6) displayed an optimum temperature at 50 degreesC and optimum pH at 5.5, a pH stability range from 4.0 to 9.5 and thermal stability up to 50 degreesC. It hydrolyzed a variety of xylan substrates mainly to xylobiose and higher short-chain xylooligosaccharides. No xylose was formed. The enzyme did not require metal ions for activity and stability.