As a prerequisite for understanding the kinetic processes involved in the OER, the relevant local reaction conditions at the interface need to be revealed. Any mechanistic study should be preceded by the identification of the stable absorbate structures . Herein, we employ a first-principles grand-canonical approach to explore the thermodynamic stability of NiOOH/water interfaces for the processes of deprotonation and alkali metal cation adsorption under varying electrochemical conditions with respect to pH and electrode potential. We will discuss the crucial importance of double-layer effects such as the adsorbate-induced surface dipole moment as well as the explicit presence of water molecules for the computed surface Pourbaix diagrams.