The electrochemical promotion of catalysis (EPOC) effect in the realm of chemistry refers to the pronounced enhancement of catalytic reactions or significant changes in the catalytic properties of a conductive catalyst in the presence of electrical currents or interfacial potentials. Also known as Non-faradaic electrochemical modification of catalytic activity (the NEMCA effect), it can increase in catalytic activity (up to 90-fold) and selectivity of a gas exposed electrode on a solid electrolyte cell upon application of a potential. This phenomenon is well documented and has been observed on various surfaces (Ni, Au, Pt,  Pd, IrO2, RuO2) supported by O, Na and proton conducting solid electrolytes.
The EPOC effect can also be utilized in a reverse manner in order to influence the selectivity of versatile heterogeneous catalytic reactions. In most cases, the electronically conductive catalyst is in metallic or metal oxide states in the form of a porous film deposited on a solid electrolyte (O or mixed O electronic conductor). The EPOC effect was firstly discovered by M. Stoukides and C. Vayenas in the early 1980s and have been widely studied by various research groups for more than 100 heterogeneous catalytic reactions of mostly gaseous molecules. The EPOC effect has been evaluated as an important phenomenon which can closely link electrocatalysis and thermal catalysis.