Abstract: Fifty-three alkaliphile bacterial isolates were collected from various fields of cosmopolitan city of Karachi, out of which 25 were alkaline protease producers. Bacillus brevis SSA1 was selected as the best enzyme producer and was used for further physico-chemical studies. B. brevis SSA1 started producing alkaline protease SSA1 after 74 h of incubation at 35°C. Activity potential of enzyme by agar-well diffusion method was found to be 800 AU mL-1. Although enzyme produced by B. brevis SSA1 was active over a wide range of pH (7-13), however, its optimal pH was found to be 8.0. The optimal temperature for enzyme activity was 60°C while enzyme activity remains stabled up to 80°C but gets inactivated at higher temperatures. Enzyme activity was totally inhibited in the presence of 5.0 mM PMSF that suggests the enzyme was related to serine alkaline protease. EDTA (inhibitor of metalloprotease) did not show any detrimental effect on the enzyme activity. Mercaptoethanol, SDS and H2O2 had no effect on alkaline protease activity. Metal ions like Cd+2, Ag+ and Ni+2 had some inhibitory effect while activity was completely lost in the presence of Zn+2. Alkaline protease SSA1 was not only stable in the presence of commercial detergent but also gave better result of washing with detergent, hence it can be used as additive in detergents for washing purposes.