This paper deals with the characterization of extracellular thermostable xylanase produced by Chaetomium globosum, an ascomycete fungus. The crude extracellular enzyme was found to have temperature and pH optima of 60-degrees-C and 5.0 respectively. The enzyme hydrolyses xylan to a mixture of xylo-oligomers. Xylobiose and xylose are the major breakdown products.