Lyonium ion

In chemistry, a lyonium ion is the cation derived by the protonation of a solvent molecule. For example, a hydronium ion is formed by the protonation of water, and CH3OH2+ is the cation formed by the protonation of methanol.

Its counterpart is a lyate ion, the anion formed by the deprotonation of a solvent molecule.

Lyonium and lyate ions, resulting from molecular autoionization, contribute to the molar conductivity of protolytic solvents.