Abstract 1. 1. Cod chymotrypsin displays higher enzyme activity compared to bovine α-chymotrypsin when assayed at low temperatures (3–15°C). 2. 2. Both enzymes are inactivated when incubated at temperatures between 60 and 70°C. 3. 3. When incubated at 99°C the cod enzyme retains about 50% of the initial activity measured at room temperature. 4. 4. Preincubation at boiling temperature renders the cod chymotrypsin active at 70°C whereas the bovine enzyme is rapidly inactivated.