In a 1671 scientific paper Robert Boyle described the reaction between iron fillings and

Lord HenryCavendish

dilute acids which results in gaseous hydrogen. The reaction may be represented as follows: Fe + H₂SO₄ → FeSO₄+ H₂

Hydrogen was originally identified as an element by the English physicist and chemist Henry Cavendish in 1766. Cavendish accurately described the properties of hydrogen but mistakenly thought the gas originated from the metal not the acid.

Later, hydrogen was named by the French scientist Antoine Lavoisier, who also proved that water was a combination of hydrogen and oxygen. The term hydrogen originates from the Greek words "hydro" meaning water and "genes" meaning generator.

The isotopes deuterium and tritium were discovered in the 20th century. Shortly after World War I (1914-1918), British physicist Francis W. Aston invented a mass spectrograph, a precursor to the mass spectrometer, a device that separates atoms by their masses. He found atoms with masses that were unusual, namely the isotopes. This provided the first clue to the existence of deuterium.

Deuterium was isolated by Harold C. Urey by distilling a sample of water multiple times. Urey received a Nobel Prize for his discovery in 1934. In the same year, the third isotope, tritium, was discovered. Tritium was first produced in 1935 by bombarding deuterium with deuterium nuclei (one proton and one neutron). Scientists have since found tritium in very small amounts in water. Tritium forms naturally in some atmospheric reactions and is the least common of the three isotopes.