Industrially important enzymes have a unique place in our lives. Exploiting industrial enzymes, a number of products have been developed and there became enormous improvement in the processes and performances of the existing products. In this monograph, an industrially important enzyme, xylanase has been studied. Xylanase has been isolated from an alkalano-thermophilic bacteria. The alkalano-thermophilic property of the enzyme may be exploited for industrial use. Therefore, it has potential for exploitation in various industries viz. paper and pulp industries, food industries, biofuel industries etc. An alkalano-thermophilic bacteria has been isolated capable of secreting xylanase under highly alkaline conditions. Xylanase having alkaline optimum pH is industrially important especially in paper pulp industries. The characterization of xylanase has been carried out which may be exploited for industrial use. Technique of solid state fermentation for production of xylanase has been optimized. The parameters optimized may be exploited for industrial production of the enzyme.