The first point is important as alkali metal hydroxides are strong bases and complete dissociation is a valid approximation at most pH values; this is nevertheless not the case at pH values close to their respective 𝑝𝐾 𝑎 -values, as can be seen in Fig. , calculated from . Both at high HER current densities in alkaline media, where the production of hydroxyl anions raises the local pH substantially and at concentrations relevant for electrolyzer applications, e.g. 6 mol/l, more than 40% of e.g. KOH would not be dissociated but remain as KOH molecules. Even at pH values as low as 13, more than 1% of LiOH and KOH molecules are not dissociated. While we are not aware of the role and significance of non-dissociated hydroxide molecules, we think this phenomenon may need to be considered, e.g. when the structure of the water interface layer at high pH values is examined .