AbstractThis study is concerned with characterizing cell‐bound inducible β‐xylosidase produced by a strain of the thermophilic bacterial genus Thermomonospora. A crude preparation of this enzyme recovered from sonicated cells of this organism displayed high activity against paranitrophenyl‐β‐xylopyranoside over a pH range of 5.5‐7.7. The temperature optimum, based on a 30‐min assay of activity, at pH 6.5 was 70°C. The crude enzyme had a thermal half‐life of approximately 1 week at 55°C and pH 6.5. Xylose inhibited the enzyme. Values of Km and Vmax are estimated from the reaction rate data as 0.82 mM and 8 U/L, respectively.