Léon Péan de Saint-Gilles (4 January 1832 – 22 March 1862) was a French chemist who worked along with Marcellin Berthelot on chemical kinetics and equilibria and attempted a mathematical formulation.
Like most wealthy Parisians of the time he was tutored at home before receiving a degree.
He set up his own analytical laboratory with the help of Théophile-Jules Pelouze and began to conduct experiments on his own.
His major work was on the use of potassium permanganate as an indicator in titrations involving ester formation with acids and alcohols.
[2] He married Pauline Thion de la Chaume, the daughter of another Paris notary, and they had two children.