Catalase and Hydrogen Peroxide Experiment

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Updated on Nov 18, 2013

How do living cells interact with the environment around them? All living things possess catalysts, or substances within them that speed up chemical reactions and processes. Enzymes are molecules that enable the chemical reactions that occur in all living things on earth. In this catalase and hydrogen peroxide experiment, we will discover how enzymes act as catalysts by causing chemical reactions to occur more quickly within living things. Using a potato and hydrogen peroxide, we can observe how enzymes like catalase work to perform decomposition, or the breaking down, of other substances. Catalase works to speed up the decomposition of hydrogen peroxide into oxygen and water. We will also test how this process is affected by changes in the temperature of the potato. Is the process faster or slower when compared to the control experiment conducted at room temperature?


What happens when a potato is combined with hydrogen peroxide?


  • 1 Potato
  • Hydrogen peroxide
  • Small glass beaker or cup


  1. Divide the potato into three roughly equal sections.
  2. Keep one section raw and at room temperature.
  3. Place another section in the freezer for at least 30 minutes.
  4. Boil the last section for at least 5 minutes.
  5. Chop and mash a small sample (about a tablespoon) of the room temperature potato and place into beaker or cup.
  6. Pour enough hydrogen peroxide into the cup so that potato is submerged and observe.
  7. Repeat steps 5 & 6 with the boiled and frozen potato sections.

Observations & Results

Watch each of the potato/hydrogen peroxide mixtures and record what happens. The bubbling reaction you see is the metabolic process of decomposition, described earlier. This reaction is caused by catalase, an enzyme within the potato. You are observing catalase breaking hydrogen peroxide into oxygen and water. Which potato sample decomposed the most hydrogen peroxide? Which one reacted the least?


You should have noticed that the boiled potato produced little to no bubbles. This is because the heat degraded the catalase enzyme, making it incapable of processing the hydrogen peroxide. The frozen potato should have produced fewer bubbles than the room temperature sample because the cold temperature slowed the catalase enzyme’s ability to decompose the hydrogen peroxide. The room temperature potato produced the most bubbles because catalase works best at a room temperature.


Catalase acts as the catalyzing enzyme in the decomposition of hydrogen peroxide. Nearly all living things possess catalase, including us! This enzyme, like many others, aids in the decomposition of one substance into another. Catalase decomposes, or breaks down, hydrogen peroxide into water and oxygen.

Want to take a closer look? Go further in this experiment by looking at a very small sample of potato combined with hydrogen peroxide under a microscope!

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