Half Cell. A half-cell consists of an electrical conductor (usually platinum) immersed in an electrolyte solution. The chemical reaction that takes place in the naturally occurring Helmholtz double layer situated between the electrolyte and the electrode in the half-cell has a unique potential associated with it. Under standard conditions (buffer concentration and absolute temperature) this potential is called the standard electrode potential. Electrochemical cells used in potentiometry are usually made up of half-cells connected by an appropriate salt bridge.

Further Information on this Topic can be found in the books of R.P.W. Scott by following the listed links