In short. Molecular hydrogen water is simply water with hydrogen gas (H2) dissolved in it. The most common way to make it at home is with an effervescent tablet, often magnesium-based, which fizzes and releases hydrogen when dropped into water; electrolysis bottles are the other route. Hydrogen is a very small, light gas that quickly escapes from an open glass, so how you prepare and drink it matters. Human research is still early and limited, and there is no authorised EU health claim for molecular hydrogen, so this guide describes what it is and how it is used, not what it does. This is information, not medical advice.
What is molecular hydrogen water?
Molecular hydrogen water is simply drinking water in which hydrogen gas, written as H2, has been dissolved. Hydrogen is the smallest and lightest molecule in existence, made up of two hydrogen atoms that together form one molecule. It has no colour, smell or taste, so hydrogen water looks and tastes like ordinary water. The hydrogen is not bound to the water in the way the H in H2O is; it is merely dissolved as a gas, in the same way that carbon dioxide is dissolved in sparkling water.
Because the gas is only dissolved and not chemically attached, it does not remain in the water forever. As soon as the water is exposed to the air, the hydrogen gradually leaves it, which is why the packaging and when you drink it are part of the subject, not an afterthought.
How do products make hydrogen water?
There are two common methods, and they do not work in the same way; each prepares one serving of hydrogen water by its own route.
The first is an effervescent tablet. These tablets are often based on elemental magnesium combined with a food acid. When the tablet is dropped into a glass or bottle of water, it reacts and fizzes, and that reaction releases hydrogen gas into the water. The tablet dissolves, the bubbles carry hydrogen, and some of that gas remains dissolved in the liquid. This is a chemical route that requires only water and a tablet.
The second is an electrolysis bottle or generator. An electric current passes through the water, splitting some of it and producing hydrogen gas in the bottle, which then dissolves in the water. This is an electrical route that requires power and a device instead of a consumable tablet.
Both aim for the same end result, namely one glass of water with hydrogen dissolved in it. They differ in cost, convenience, how efficient and repeatable the result is, and how the gas is kept in the water. Neither method says anything about quality or effects; they merely describe how you arrive at one glass of hydrogen water.
What does concentration mean?
The amount of hydrogen dissolved in water is usually described as a concentration, in parts per million (ppm) or as milligrams of hydrogen per litre. As a general principle, a higher figure means more gas is dissolved in the same volume of water. Because hydrogen is so light, the actual dissolved mass is always very small, and the amount per litre remains real but modest.
Two honest points matter here. First, hydrogen is only moderately soluble in water, so there is a natural limit to how much can dissolve at normal pressure. Second, every figure is a snapshot at the time of preparation; the concentration falls as the gas escapes into the air. A figure alone does not tell you how much hydrogen remains by the time you drink it, and that depends on the method, the packaging and the time elapsed.
Tablet in a sealed glass or an open bottle: what is the difference?
Because hydrogen is such a small, light gas, it quickly escapes from water when there is open air above it. How you contain the gas changes how much remains dissolved. The comparison below is descriptive.
| Setup | How the gas behaves | General characteristic (for information) |
|---|---|---|
| Tablet in a sealed container | Pressure builds as the tablet fizzes, allowing more gas to remain dissolved | Designed to keep hydrogen in the water until opened |
| Tablet in an open glass | Hydrogen escapes into the air as it is produced and afterwards | Simple, but more gas is lost before drinking |
| Electrolysis bottle | Gas is produced inside and dissolves, then escapes once opened | Repeatable device, although the result still declines in air over time |
| Pre-packaged hydrogen water | Sealed at the source, but a permeable bottle slowly allows gas to escape | Packaging material and storage time determine what remains |
The common thread is simple physics: a closed environment helps keep the gas dissolved, while open air allows it to escape. That is why many tablet products are used in one filled, sealed glass or bottle and drunk without a long delay, which retains the gas more efficiently.
How do people use hydrogen water?
In practice, people usually prepare it fresh and drink it without waiting. With a tablet, that means filling one glass or bottle, dropping in the tablet, allowing it to dissolve, and drinking once the reaction has finished. With an electrolysis device or pre-packaged water, it means drinking shortly after production or opening, preferably in one go. The shared idea across all methods is to drink while the gas is still dissolved, because an open container loses hydrogen over time. Our own tablet-based approach is described with our molecular hydrogen. None of this implies a health outcome; it simply reflects how the gas behaves.
What does the research say?
This is where honesty matters most. Human research into molecular hydrogen water is still early and limited. Researchers have studied hydrogen water in a number of small studies and in laboratory settings, but the studies are generally small, differ in design and do not lead to a single settled conclusion. Early findings are not the same as proven effects, and one small study is no reason to expect a particular outcome.
Crucially, there is no authorised EU health claim for molecular hydrogen. This means that no health benefit of any kind may be presented as established fact. That is why this article, and any responsible brand, tells you what hydrogen water is, how it is made and how the gas behaves, rather than promising what it will do for you. Saying scientists have looked at a subject is not the same as saying it has been proven, and we keep that boundary clear.
Is hydrogen water safe?
Hydrogen water is generally considered low risk for healthy adults because it is water with a minute amount of inert, non-toxic gas dissolved in it, and the gas itself is not a medicine. That said, it is not a remedy and should not be used as one. Effervescent tablets are often magnesium-based, and magnesium in higher amounts can have a laxative effect, so follow the product instructions and stay within one recommended serving at a time. If you are pregnant or breastfeeding, take medication, or have a condition such as impaired kidney function, consult a doctor or pharmacist first. A hydrogen-generating device must be used according to its own safety instructions. Supplements and functional drinks are no substitute for a varied diet or medical care.
Frequently asked questions
What is molecular hydrogen water?
It is simply drinking water with hydrogen gas (H2) dissolved in it. The hydrogen is not bound to the water; it is merely dissolved as a gas, like the carbon dioxide in sparkling water, and it leaves the water when exposed to the air.
How do hydrogen tablets work?
An effervescent tablet, often based on magnesium and a food acid, reacts and fizzes when it is dropped into water, releasing hydrogen gas that dissolves in the liquid. The tablet itself dissolves in the process.
What is the difference between tablets and an electrolysis bottle?
A tablet produces hydrogen through a chemical reaction in the water and requires only water and the tablet. An electrolysis bottle passes an electric current through the water to generate hydrogen and requires power and a device. Both aim to produce water with hydrogen dissolved in it.
Why is a sealed container important?
Hydrogen is a very small, light gas that quickly escapes into open air. One sealed glass or bottle helps keep the gas dissolved efficiently until you drink, while an open container loses hydrogen over time.
Does hydrogen water have an EU health claim?
No. There is no authorised EU health claim for molecular hydrogen, and human research is still early and limited. That is why we describe what hydrogen water is and how it is used, not what it does for your health.
Sources
- Regulation (EC) No 1924/2006 on nutrition and health claims made on foods (governing health claims for foods and food supplements in the EU).
- EU Register of Nutrition and Health Claims made on foods (no authorised health claim for molecular hydrogen is listed). ec.europa.eu
- General source on the chemistry and solubility of hydrogen gas (H2) in water (standard chemistry and physical properties sources).
Written by the NOTFORTOMORROW editorial team. How we conduct our research: we base factual statements on the official EU claims register and general scientific sources, cite our sources and date our reviews. This article is information, not medical advice; consult a qualified professional about your situation. Last reviewed: 2026-06-06.
