Henri Moissan is credited with discovering (more precisely, first isolating) elemental fluorine in 1886.

Who actually “discovered” fluorine?

  • Elemental fluorine was first successfully isolated by the French chemist Henri Moissan in 1886 using electrolysis of potassium fluoride in hydrofluoric acid.
  • For this work, Moissan received the 1906 Nobel Prize in Chemistry, and modern chemistry texts generally name him as the discoverer of fluorine.

Earlier work before Moissan

  • The mineral fluorspar (fluorite, calcium fluoride) was described as early as 1529 by Georgius Agricola, long before fluorine was known as an element.
  • In the 18th and early 19th centuries, chemists like Carl Wilhelm Scheele, André-Marie Ampère, and Sir Humphry Davy studied compounds of fluorine and suspected a new element, but they could not isolate it because of its extreme reactivity and the dangers of hydrofluoric acid.

TL;DR: When people ask “who discovered fluorine,” the accepted answer is Henri Moissan, who first isolated elemental fluorine in 1886, building on centuries of earlier work on fluorine-containing minerals and acids.