Why is Hydrogen Flammable? (+ 3 Surprising Facts to Know)

Yes, hydrogen is flammable. 1 It is highly flammable and can easily ignite at room temperature. Hydrogen fires are also very difficult to extinguish. 2

Well, this was just a simple answer. But there are few more things to know about this topic which will make your concept super clear.

So let’s dive right into it.

Key Takeaways: Is hydrogen flammable?

  • Hydrogen is a highly flammable gas that can easily ignite at room temperature and forms a flammable mixture with oxygen
  • It has a low ignition energy and is a very reactive gas, which can react with oxygen to form water and sustain the fire. 
  • Liquid hydrogen is even more volatile and easier to ignite than gaseous hydrogen, and it requires special safety precautions and equipment for handling and storing. 

Explanation: Why is hydrogen flammable?

Hydrogen is flammable because it is a very light gas that is easily ignited. It has a wide range of flammable concentrations in air, meaning that it can easily form a flammable mixture with oxygen. 3

Hydrogen also has a low ignition energy, meaning that it can be ignited by a small spark or flame. 4

Hydrogen is also a very reactive gas. It can react with oxygen to form water, which is a very exothermic reaction. This means that the reaction releases a lot of heat, which can help to sustain the fire. 5

For these reasons, hydrogen is considered to be a very flammable gas. It is important to take precautions when handling hydrogen to avoid fires and explosions.

Is liquid hydrogen flammable?

Yes, liquid hydrogen is highly flammable. Like gaseous hydrogen, it can easily ignite and react with oxygen to produce a large amount of heat and light in a process known as combustion. 6

When hydrogen is in its liquid state, it is actually more volatile and easier to ignite than when it is in its gaseous state. This is because liquid hydrogen is denser and contains more hydrogen molecules per unit volume, making it more reactive. 7

Furthermore, liquid hydrogen has a very low boiling point of -252.87 °C, which means that it can quickly evaporate and form a combustible gas mixture with air. 8

If this gas mixture is exposed to a source of ignition, such as a spark, it can easily catch fire and cause an explosion.

Because of its flammable nature, handling and storing liquid hydrogen requires special safety precautions and equipment. 

This includes storing it in specially designed containers and handling it with care to avoid ignition sources.

Is hydrogen flammable without oxygen?

Hydrogen itself is not flammable without oxygen or another oxidizing agent. 9 This is because combustion, which is the process of burning that produces heat and light, requires the presence of both a fuel (in this case, hydrogen) and an oxidizing agent (usually oxygen).

When hydrogen is burned in the presence of oxygen, it reacts with the oxygen to form water (H2O) and releases energy in the form of heat and light. 

Without oxygen or another oxidizing agent, the hydrogen will not undergo combustion and will not burn.

However, it’s important to note that hydrogen gas can still be a fire hazard even without oxygen present. 

This is because hydrogen gas is highly flammable and can ignite or explode in the presence of certain ignition sources, such as sparks or heat sources. 

Additionally, hydrogen gas can displace oxygen in a confined space, potentially leading to suffocation. 10 So while hydrogen itself is not flammable without oxygen, it still requires careful handling and storage to prevent accidents.

Further reading

Does Hydrogen have Neutrons?
Is Helium Flammable?
Why Is Helium a Noble Gas?
Is Helium a Metal?
Why is Hydrogen a Nonmetal?

About author

Jay is an educator and has helped more than 100,000 students in their studies by providing simple and easy explanations on different science-related topics. He is a founder of Pediabay and is passionate about helping students through his easily digestible explanations.

Read more about our Editorial process.


  1. Safe Use of Hydrogen. (n.d.). Energy.gov. https://www.energy.gov/eere/fuelcells/safe-use-hydrogen
  2. NHTSA https://www.nhtsa.gov/sites/nhtsa.gov/files/811816.pdf
  3. NASA https://www.nasa.gov/pdf/513855main_ASK_41s_explosive.pdf
  4. Energy.gov https://www1.eere.energy.gov/hydrogenandfuelcells/tech_validation/pdfs/fcm03r0.pdf
  5. Kujan, S. L. (n.d.). Explosive Reaction of Hydrogen and Oxygen Using Balloons. Explosive Reaction of Hydrogen and Oxygen Using Balloons. https://rutchem.rutgers.edu/cldf-demos/1028-cldf-demo-balloons
  6. introducing energy changes during reactions. (n.d.). Introducing Energy Changes During Reactions. https://www.chemguide.uk/14to16/energy/intro.html
  7. IATA.org https://www.iata.org/contentassets/d13875e9ed784f75bac90f000760e998/fact_sheet7-hydrogen-fact-sheet_072020.pdf
  8. The boiling point of liquid hydrogen, determined by hydrogen and helium gas thermometers. (1901, September 30). Proceedings of the Royal Society of London, 68(442–450), 44–54. https://doi.org/10.1098/rspl.1901.0011
  9. Why doesn’t the planet Uranus explode if it contains so much hydrogen and methane? (2015, April 3). Science Questions With Surprising Answers. https://wtamu.edu/~cbaird/sq/2015/04/03/why-doesnt-the-planet-uranus-explode-if-it-contains-so-much-hydrogen-and-methane/
  10. Energy.gov https://www1.eere.energy.gov/hydrogenandfuelcells/pdfs/h2_safety_fsheet.pdf

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top