Background <p>Renewable energy sources have gained importance due to environmental concerns and rising energy costs. Plant biomass is an abundant and eco-friendly resource, with xylan as a major hemicellulose component requiring xylanases for its degradation. Thermostable xylanases are valuable for their stability under harsh conditions. This study aimed to identify and characterize novel thermophilic xylanases for sustainable biotechnological applications.</p> Methods and Results <p>A novel glycoside hydrolase family 10 (GH10) endo-1,4-β-xylanase from the thermophilic bacterium <i>Anoxybacteroides tepidamans</i> was identified, cloned, overexpressed, and biochemically characterized. The 39.06&#xa0;kDa protein showed the classical (α/β)₈-barrel fold characteristic of GH10 xylanases. The recombinant enzyme (<i>Atep</i>Xyn) was purified with a 2.46-fold purification, and its specific activity was 87.52 U/mg protein. Maximum enzymatic activity over beechwood xylan was obtained at 65&#xa0;°C and pH 7.0; however, a broad range of activity was observed between pH 5.5 and 8.0, and at 45–65&#xa0;°C. Xylanase activity was stimulated by Mn²⁺, Co²⁺, and Sn²⁺, but strongly inhibited by Cu²⁺, Ca²⁺, Hg²⁺, Fe³⁺, and Ag²⁺. Notably, the half-life of <i>Atep</i>Xyn at 65&#xa0;°C was 12&#xa0;h. The <i>K</i>_<i>m</i>, <i>V</i>_<i>max</i>, <i>k</i>_<i>cat</i>, and <i>k</i>_<i>cat</i><i>/K</i>_<i>m</i> values of the enzyme were 3.28 ± 0.16&#xa0;mg mL^− 1, 60.816 ± 0.1 µmol min^− 1 mg^− 1, 79.41&#xa0;s^− 1, and 24.17 mL·mg⁻¹·s⁻¹, respectively.</p> Conclusions <p>The thermophilic character of <i>Atep</i>Xyn, together with its activity across a broad temperature and pH range and its high catalytic efficiency toward beechwood xylan, makes it a promising candidate for industrial applications in biomass conversion, biofuel production, and other biotechnological processes requiring robust xylan-degrading enzymes.</p>