Who discovered the Mole? Who discovered the mole? An italian scientist in 1811 named Amadeo Avogadro discovered the concept of the mole. Who was he? Lorenzo Romano Amedeo Carlo Avogadro, conte di Quarequa e di Cerreto (1776 - 1856), was born in Turin, Italy, on 9th August, 1776. When Avogadro was becoming a scientist, chemistry was still in its infantcy. The Law of Definite Proportions and the Law of Multiple Proportions were well accepted by 1808, at which time John Dalton published his New System of Chemical Philosophy. In 1811, Avogadro published an article. He stated that Dalton had confused the atom and the molecule. What Dalton thought was an atom of oxygen was actually a molecule of two atoms.This is why two molecules of hydrogen can combine with one molecule of oxygen to produce two molecules of water. Avogadro suggested that equal volumes of all gases at the same temperature and pressure contain the same number of molecules. This is now known as Avogadro's principal. Avogadro's number as we know it today is VERY large. (Infact if you go here, you can see how big it actually is.) It is accepted to be 6.0221367 x 10^23 This number was not determined by Avogadro, but is named in honor of him. (It must be recognised that Avogadro had no knowledge of "moles" or Avogadro's number. These were later determined by someone else and named in honor of him.)