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An organic solvent-tolerant bacterium producing organic solvent-stable protease was isolated from fishing industry wastewater and identified as B. cereus. The enzyme retained more than 95% of its initial activity after pre-incubation 24h at 30°C in the presence of 25% methanol, DMSO, acetonitrile and DMF. Above 37°C, Ca²⁺ was required for enzyme activity. The optimum temperature for the protease activity was at 60°C in the presence of 2mM Ca²⁺ and 50°C in the absence of Ca²⁺. At 60°C, Ca²⁺ (2mM) stimulated the protease activity by 500%. Other bivalent metal ions such as Mg²⁺ and Mn²⁺ also increased activity by 285 and 157%, respectively, while Zn²⁺ and Cu²⁺ had a strong inhibitory effect. Thermostability of the enzyme was enhanced by Ca²⁺ at temperature values above 40°C. In the presence of 10mM Ca²⁺, the enzyme retained 100, 93 and 26% of its initial activity after heating for 15min at 55, 60 …