To summarize, we demonstrate that the activation of a nickel oxide OER catalyst in LiOH, NaOH, KOH, or CsOH affects both the structure and the surface of the OER active NiOOH phase. After activation, increasing amounts of alkali metal cations are adsorbed on the catalyst in the order Li + < Na + < K + < Cs + , whereby the layers of the NiOOH layered double hydroxide structure are opened up to form a more γ-like NiOOH phase. Additionally, from LiOH to CsOH an increased deprotonation of the NiOOH surface is observed. Importantly, a more deprotonated surface is shown to result in a more effective dissociation of water on that surface. As the dissociation of water is a crucial step in many OER mechanisms, an improved H2O dissociation might directly correlate with the observed decreased OER overpotential. Yet, the discussion highlights that the facilitation of H2O dissociation can be a result of many intertwined phenomena. Structural bulk and surface changes, pH changes, changes in the electric double layer, and probably even more aspects need to be considered in future studies about the impact of alkali metal cations on nickel-based anodes for the alkaline water electrolysis.