Xylanolytic Bacillus pumilus SS1 grew well at highly alkaline pH (9–11) and at moderately high temperature (25–55 1C) and successfully utilized wheat bran as the sole carbon source and produced considerable titer of xylanase. Maximum enzyme production occurred at medium pH 8 and at 45 1C. The enzyme purified (2.97-fold) with ammonium sulfate fractionation and carboxymethyl sephadex chromatography, showed molecular weight of 25 kDa, low Km (2.7 mg/ml) and reasonably good Vmax (36 mmol/mg/min). Enzyme showed maximum activity at pH 6–8, and at 40–50 1C. Enzyme was inhibited by HgCl2, CoCl2, MnSO4, MgCl2, phenylmethylsulphonylfluoride and CaCl2, while FeCl2 caused slight stimulation.