Xylanase was produced with Bacillus subtilis (pJXI8), constructed previously, which contains Clostridium thermocellum xylanase gene expressing with a strong Bacillus promoter. The enzyme hydrolyzed oat spelt xylan to mostly xylobiose and xylotriose which are preferred for industrial applications. The optimal temperature and pH for the activity of this enzyme were 60-degrees-C and 5.4, respectively, with moderate stability under these conditions.