A bleach-stable, thermotolerant, alkaline protease for detergent formulation from a newly isolated Bacillus SB5 is reported. Most (85%) activity of the enzyme was retained in the presence of 10% (v/v) H2O2 and 1% SDS (w/v) at 40 degrees C, after 1 h. The enzyme was optimal at pH 10 and 60 degrees C to 70 degrees C. Enzyme activity was enhanced 30 to 80%; in presence of ionic and non-ionic detergents, surfactants and commercial detergents or bleach.