Decomposition Potential
The minimum voltage that must be applied to an electrolytic cell before continuous electrolysis begins.
Unit
V
In depth
Below this threshold only a tiny transient current flows as the electrodes polarise. The decomposition potential equals the theoretical reverse emf of the cell plus the overpotentials at both electrodes, so it is always larger than thermodynamics alone would predict.
Examples in the real world
Water theoretically needs 1.23 V but in practice requires about 1.7 V because of oxygen overpotential.