A collaborative ultrafast spectroscopy and ab initio molecular dynamics simulations study shows that proton vacancies in the form of hydroxide/methoxide ions are as relevant for proton transfer between acids and bases as hydrated excess protons, thus pointing for a clear demand for refinement of the microscopic picture for aqueous proton transport – in solution as well as in hydrogen fuel cells or transmembrane proteins – away from currently often assumed dominant role of hydrated excess protons.
