High levels of extracellular xylanase activity (994.50 IU/ml) produced by Geobacillus thermodenitrificans C5 originated gene was detected when it was expressed in E. coli BL21 host. Thermostable xylanase (GthC5Xyl) was purified to homogeneity and showed a molecular mass of approximately 44 kDa according to SDS-PAGE. The specific activity of the purified GthC5Xyl was up to 1243.125IU/mg with a 9.89-fold purification. The activity of GthC5Xyl was stimulated by CoCl2, MnSO4, CuSO4, MnCl2 but was inhibited by FeSO4, Hg, CaSO4. GthC5Xyl showed resistant to SDS, Tween 20, Triton X-100, beta-Mercaptoethanol, PMSF, DTT, NEM and DEPC, SDS, and EDTA. A greater affinity for oat spelt xylan was exhibited by GthC5Xyl with maximum enzymatic activity at 60 degrees C and 6.0 pH. The activity portrayed by GthC5Xyl was found to be acellulytic with stability at high temperature (70 degrees C-80 degrees C) and low pH (4.0 to 8.0). Xylobiose and xylopentose were the end products of proficient oat spelt xylanase hydrolysis by GthC5Xyl. High SDS resistance and broader stability of GthC5Xyl proves it to be worthy of impending application in numerous industrial processes especially textile, detergents and animal feed industry.