A novel alkaline alpha -amylase of Bacillus sp. TS-23 was purified to homogenous state from the culture medium of recombinant Escherichia coli by ammonium sulphate precipitation and successive Sephacryl(TM) S-100 and pBE(TM) 94 chromatography. The molecular mass of the purified enzyme was estimated to be 65 kDa by electrophoresis. The pH and temperature optima for amylase activity were pH 9.0 and 60 degreesC, respectively. The enzyme was stimulated by Mn2+ Co2+ and Fe2+ ions but was strongly inhibited by Hg2+ and Cu2+ and by the well-characterized inhibitors, diethylpyrocarbonate and N-bromosuccinimide. The enzyme was active in the presence of 8% sodium dodecyl sulphate (SDS). Bacillus sp. TS-23 alpha -amylase was stable when it was preincubated with 6% SDS for upto 1 h at 30 degreesC, while inactivation was observed at 60 degreesC. Under optimal condition, this enzyme was able to attack the alpha -1.4 linkages in soluble starch, amylose, amylopectin and glycogen to generate maltopentaose as the major end product.