The Wien effect is the experimentally-observed increase in ionic mobility or conductivity of electrolytes at very high gradient of electrical potential.
[1] A theoretical explanation has been proposed by Lars Onsager.
[2] A related phenomenon is known as the Second Wien Effect or the dissociation field effect, and it involves increased dissociation constants of weak acids at high electrical gradients.
[3] The dissociation of weak chemical bases is unaffected.
The effects are important at very high electrical fields (108 – 109 V/m), like those observed in electrical double layers at interfaces or at the surfaces of electrodes in electrochemistry.