An alkali-tolerant fungus Aspergillus fischeri Fxn1 isolated from xylan enrichment grew in the pH range 5-10 and secreted an extracellular cellulase-free xylanase. Arabinose, lactose, maltose, cellobiose and glucose induced low levels of xylanase (1.8-9.0 IU/ml),whereas xylose,xylan and wheat bran induced higher level (34-45 IU/ml). CMcellulose and FPcellulose did not support growth. The optimum pH of xylanase was 6.0-6.5 and it was stable in a wide range of pH 5-9.5. The optimum temperature was 60 degrees C and it was stable upto 55 degrees C. The half-lives at 50 and 55 degrees C were 240 and 40 min. respectively. This enzyme released reducing sugars from pulp at pH 9.0 and 40 degrees C.