Standard electrode potential

In electrochemistry, standard electrode potential ${\displaystyle E^{\ominus }}$, or ${\displaystyle E_{red}^{\ominus }}$, is a measure of the reducing power of any element or compound. The IUPAC "Gold Book" defines it as; "the value of the standard emf (electromotive force) of a cell in which molecular hydrogen under standard pressure is oxidized to solvated protons at the left-hand electrode".