Marcel Pourbaix (16 September 1904 – 28 September 1998) was a Belgian chemist and pianist. He performed his most well known research at the University of Brussels, studying corrosion.  His biggest achievement is the derivation of potential-pH, better known as “Pourbaix Diagrams”.  Pourbaix Diagrams are thermodynamic charts constructed using the Nernst equation and visualize the relationship between possible phases of a system, bounded by lines representing the reactions that transport between them.  They can be read much like a phase diagram.
In 1963, Pourbaix produced "Atlas of Electrochemical Equilibria", which contains potential-pH diagrams for all elements known at the time.  Pourbaix and his collaborators began preparing the work in the early 1950s.