How fast does the enzyme catalase break down hydrogen peroxide? Catalase is found in living tissues like liver and potato. When it meets hydrogen peroxide, it triggers a rapid fizzing reaction that produces oxygen gas. You place a small amount of liver or potato extract in a test tube. Then you pour in diluted hydrogen peroxide and immediately start timing. The reaction creates a rising column of froth. You measure its height with a ruler. The reaction rate equals froth height divided by time. You can test different variables like temperature to see how they change the speed. Keeping extract on ice before use helps preserve the enzyme.