Abstract: An aerobic, alkaliphilic, xylanolytic bacterium was isolated from local Soda lake. The strains were isolated on xylan agar medium and screened by xylanolysis method. The bacterial strains ( StA, StB, StC and StD) were identified based on morphological, biochemical and physiological characters. On the basis of these tests, the four strains were identified as belonging to the genus Bacillus. Alkaline Xylanases produced by four different strains of Bacillus sp. were also characterized. The optimal pH and temperature were pH 8.0 for and 50°C StA and pH 8.5 and 55°C for strain StD and pH 9.0 and 55°C for strains StB and StC. Under these conditions the following activities were found after 10 min in the presence of 0.7% oat spelt xylan; 302, 233, 189 and 207 U ml-1, respectively, for the four strains. The enzymes were stable at 40-50°C, with 45% of the xylanases activity remaining after 2 hours for the enzymes of strain StB and 55% for the other four strains. Taking into account the conditions under which Kraft pulps are bleached during the manufacture of paper, Xylanases from Bacillus sp. exhibit favorable potential for application to bleaching in the paper making process.