Hydrogen peroxide (H2O2)


  • Primary spotless use: Disinfectant, bleach, deodoriser, all-round cleaner
  • No toxic by-products, harmless in diluted form, many uses
  • Other uses: Water, air and soil treatment, wound cleaner and antiseptic, propellant
  • Main cleaning action: Powerful oxidiser
  • Forms part of a healthy environment – natural purification system for air, water and soils and helps plant and animal cells fight disease
  • Breaks down readily into water and oxygen only
  • One of the most powerful oxidisers known, as well as the most versatile


This truly amazing substance is produced in nature when sunlight shines on water or air passes through it, when rain passes through the ozone layer, and in the cells of plants and animals (including humans). In cells it functions as an important part of the immune system and is easily broken down into water and oxygen.

Despite its benefits, hydrogen peroxide at high strength is highly corrosive and toxic if swallowed, so if you do buy or use high strength peroxide, store and use it with care. For most home uses, a 3% (10 volume) solution which is available cheaply at pharmacies is what you are after (we are always referring to 3%, or 10 volume, solution below, unless otherwise specified). At this dilution it is safe to handle and extremely useful (but still store it carefully out of children’s reach, do NOT drink it other than under medical supervision, and never put it in your eyes.)

It should be stored away from sunlight in a dark air-tight container.

In case you don’t want to use hydrogen peroxide, we have always given an alternative using other ingredients.

What is it?

Hydrogen peroxide is a colourless or pale blue liquid resembling water but slightly more viscous. It consists of water (H2O) plus an extra oxygen molecule (hence H2O2). It is unstable in the presence of light, air and other compounds, and readily releases its extra oxygen molecule, leaving water. Oxygen in nature consists of two oxygen molecules (O2) and is very stable. But a single oxygen molecule, such as those released when hydrogen peroxide breaks down, is very reactive and acts as a powerful oxidising and disinfecting agent.

Hydrogen peroxide is sold and used in varying dilutions, depending on its intended purposes. For example, 3% hydrogen peroxide (which is suitable for almost all the purposes mentioned on this site) is a solution of 3% peroxide and 97% water. Hydrogen peroxide is also referred to by volume. This way of distinguishing peroxide strengths refers to the volume of oxygen that will be produced when the H2O2 is exposed to a reacting agent, such as air. Hence one cup of 10 volume (or 3%) hydrogen peroxide can produce 10 cups of oxygen. This ability to produce large volumes of oxygen (as well as heat) is why it can be hazardous and is useful in rocketry at high strengths (e.g. 60% = 200 volume). It must be stored and handled correctly to remain free from impurities and away from light. When stored properly it is very stable. Hydrogen peroxide that is commonly for sale at pharmacies has chemical stabilisers added to it; food grade hydrogen peroxide is free from stabilisers and recommended for any medicinal uses after being diluted to 3% with distilled water, and further diluted to around 0.1% (i.e. 2-20 drops of 3% in a cup of water) for internal use.

For home cleaning purposes, one part of 40 volume (12%) hydrogen peroxide can be diluted with three parts of ordinary tap water to make 4 parts of 10 volume (3%) hydrogen peroxide.

How is it made?

In nature

As rain or snow pass through the ozone layer, some water molecules pick up an extra oxygen molecule and become hydrogen peroxide. (Unstable ozone, O3, is made up of 3 oxygen molecules.) The hydrogen peroxide in rain then reacts with air-borne toxins, effectively cleaning the air of pollution and leaving the air fresh after rain.

Water also forms some hydrogen peroxide molecules when exposed to sunlight or when lots of air containing oxygen is driven through it, as in a waterfall or rapid. This is why fast running mountain water is generally clean and germ free. The hydrogen peroxide acts as a natural water purifier by oxidising and destroying waterborne toxins. High altitude springs or those fed by high altitude snow melt (such as Lourdes) are particularly high in H2O2, one reason for their well-known healing properties. Simply shaking water and air vigorously in a container will produce some hydrogen peroxide and so increase the water’s purity and benefits.

Hydrogen peroxide is also produced in the cells of most living things. All cells that use oxygen in their metabolism to generate energy from food (aerobic respiration), produce peroxide as a by-product. It is harmlessly decomposed by enzymes (peroxidises) into water and oxygen, the singlet oxygen molecules (O) being used to fight off pathogens and toxins, or destroyed by antioxidants so as not to harm healthy cells. Some cells in our bodies such as T-cells and white blood cells also produce and release hydrogen peroxide to fight disease. Most unhealthy cells (e.g. cancer cells, viruses and unhealthy bacteria) are anaerobic and do not have an enzyme coating to protect them from singlet oxygen molecules, which destroy them. Hydrogen peroxide (along with protective antioxidants) is found in raw vegetables and fruits, giving them much of their health benefit; but the extra oxygen is driven off in cooking.

Commercial production

Nearly all hydrogen peroxide is currently produced using the auto-oxidation, or AO process. Producers use a working solution of alkylated anthraquinones. The solution is alternately hydrogenated with a catalyst (nickel or palladium) to produce hydrogen, and then air oxidised, when compressed air is bubbled through the solution. The oxygen in the air combines with the hydrogen to form hydrogen peroxide. This peroxide (about 40% diluted) is extracted and the working solution concentrated so that the cycle can repeat itself. The 40% peroxide is known as crude hydrogen peroxide and is distilled to 60% for storage. This storage H2O2 can then be either diluted or further distilled for other uses. For non-food grade peroxide, stabilisers are added to prevent decomposition (into water and large volumes of oxygen), which is sped up by the presence of any contaminants. Food grade peroxide is purified further and no stabilisers are added.

What is it used for?

The major industrial use of hydrogen peroxide is as a bleach for pulp and paper. Other applications are expanding as it is becoming recognised as an effective environmentally benign alternative to chlorine bleach. It is also used as a propellant (e.g. for rockets) because of its ability (at high strengths) to release large volumes of oxygen very quickly in the presence of certain other compounds (see more below).

With more and more pollution, less hydrogen peroxide now reaches the ground when rain falls, as it is used up oxidising airborne toxins as the rain falls. This is sad for plants as it is also the H2O2 in rainwater that makes it so much better for plants than tap water. It oxygenates and de-compacts soil around roots and gets rid of bacteria. To compensate, farmers and gardeners are beginning to spray plants with hydrogen peroxide solution or to add it to their irrigation water to boost their plants’ growth and help the plants stay healthy.

Hydrogen peroxide is also being used to treat and purify waste and drinking water, contaminated soil and groundwater, and industrially polluted air and water. It can be used to boost septic tanks and de-compact soil and as a healthy alternative to chlorine in spas and pools.

Living cells produce hydrogen peroxide which helps them fight disease (see above), and it has many medicinal uses that harness this ability. These uses range from wound and instrument cleaning to cancer treatment. Babies get their first dose of hydrogen peroxide therapy with their mother’s breastmilk, which contains it. There is even more in colostrum (first milk), where it is thought to help stimulate the baby’s immune system. To read about how a massive range of ailments can be treated using food grade hydrogen peroxide, see here.

Hydrogen peroxide has myriad uses in the home, one of which is to replace chlorine bleach. “Bleach” is handy but has the ability to form toxic by-products such as dioxin. There is some debate about whether this should be a concern for home users, but personally we hate the way it makes one’s throat hurt and eyes sting and would not want it in our home when there is an alternative that is actually GOOD for the environment. Plus, hydrogen peroxide is amazingly versatile, having household cleaning and personal care uses ranging from loo cleaner to tooth cleaner.

See here and here for information and many, many other ways to use hydrogen peroxide.

What is its history?

As you can see from much of the above, hydrogen peroxide has always been nature’s own cleaner and disinfectant. Being found in rainwater, man’s earliest drink, as well as raw foods, its health benefits were being experienced ever since man first existed. With our modern processed foods and piped water supplies, we have lost many of these benefits.

H2O2 was first isolated in a laboratory and so discovered in 1818 by Louis Jacques Thénard, and became a commercial product in the 1880s. It was produced by burning barium salts to produce barium peroxide which then yields hydrogen peroxide when dissolved in water. Its initial market was for bleaching the straw hats that were fashionable at the time.

As demand grew methods of production changed until now almost all peroxide is produced using the AO method described above.

Hydrogen peroxide has been used for rocket engine propulsion since the Second World War. The most well known application was in the V2 rocket. It was also used as a propellant in space exploration. More complicated, expensive and environmentally harmful fuels later replaced peroxide in space exploration and the military, but there has been renewed interest recently because of its advantages of simplicity, cost and minimal environmental impact. It is still used to disinfect spacecraft, showing that it is probably good enough for your kitchen and bathroom!

Its medicinal value was recognised at least as early as shortly after the First World War, when some doctors successfully treated a pneumonia epidemic with intravenous hydrogen peroxide. With the rise of prescription drugs from the 1940s, however, research and marketing attention was diverted away from medicinal use of peroxide because it is an inexpensive naturally occurring substance that cannot be patented to make money for the pharmaceutical industry. While it is dangerous and even lethal in high concentrations and if used incorrectly, the same can be said for most medicines. When used correctly, at the low concentrations recommended, it has no side effects or disadvantages. A resurgence of interest in its health benefits (including its potential to treat cancer and emphysema) must surely be welcomed.