Hydronium vs. Hydroxonium — What's the Difference?

In chemistry, hydronium (hydroxonium in traditional British English) is the common name for the aqueous cation H3O+, the type of oxonium ion produced by protonation of water. It is often viewed as the positive ion present when an Arrhenius acid is dissolved in water, as Arrhenius acid molecules in solution give up a proton (a positive hydrogen ion, H+) to the surrounding water molecules (H2O).

(chemistry) The cation obtained by reacting a proton with water - H₃O⁺; hydronium

A hydrated hydrogen ion, H3O+. Also called hydronium ion.

(inorganic chemistry) The hydrated hydrogen ion, H₃O⁺.