To date, xylanases have expanded their use in many processing industries, such as pulp, paper, food, and textile. This study aimed the production and partial characterization of a thermostable xylanase from a novel thermophilic anaerobic bacterium Caldicoprobacter algeriensis strain TH7C1(T) isolated from a northeast hot spring in Algeria. The obtained results showed that C. algeriensis xylanase seems not to be correlated with the biomass growth profile whereas the maximum enzyme production (140.0 U/ml) was recorded in stationary phase (18 h). The temperature and pH for optimal activities were 70 A degrees C and 11.0, respectively. The enzyme was found to be stable at 50, 60, 70, and 80 A degrees C, with a half-life of 10, 9, 8, and 4 h, respectively. Influence of metal ions on enzyme activity revealed that Ca+2 enhances greatly the relative activity to 151.3 %; whereas Hg2+ inhibited significantly the enzyme. At the best of our knowledge, this is the first report on the production of xylanase by the thermophilic bacterium C. algeriensis. This thermo- and alkaline-tolerant xylanase could be used in pulp bleaching process.