The mole in chemistry does not have a single, universally agreed-on “discoverer,” but two names come up most often in history: Amedeo Avogadro and Wilhelm Ostwald.

Quick Scoop

Who gets the main credit?

  • Amedeo Avogadro (1776–1856)
    Avogadro’s 1811 hypothesis (“equal volumes of gases at the same temperature and pressure contain equal numbers of particles”) laid the theoretical foundation for the mole concept and what later became Avogadro’s number.

Because his work links amount of substance to a specific number of particles, Avogadro is often informally credited with the “idea” behind the mole, especially in textbooks and Mole Day celebrations.

  • Wilhelm Ostwald (1853–1932)
    The actual word “mole” (from the German Molekül , molecule) and its use as a unit in chemistry were introduced by the German chemist Wilhelm Ostwald in the 1890s.

Modern educational sources explicitly say that “the word mole was introduced by Wilhelm Ostwald in 1896,” making him the person who coined and formalized the term for the unit.

So, who “discovered the mole in chemistry”?

  • If the question is about the name and unit “mole” :
    • The answer is Wilhelm Ostwald , who introduced the term and used it systematically in chemistry around 1896.
  • If the question is about the underlying idea of relating gas volume and particle count (what a mole represents):
    • The key figure is Amedeo Avogadro , whose gas law made it possible to define a standard “amount of substance” linked to a fixed number of particles.

In many school-level answers, saying “Wilhelm Ostwald introduced the term mole; Avogadro provided the theoretical basis” will cover what examiners are looking for.

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