The self-assembly of adsorbed molecules into structured adlayers on the electrode’s surface provides a straightforward way to modify the interface. Moreover, the formation and properties of the formed adlayers can be controlled by the applied potential, which offers fascinating prospects for the development of molecular switches1, thin film transistors2, and sensors3. Ionic liquids are a class of unique electrolytes, which properties differ notably from common aqueous or organic electrolytes. For example, due to good electrochemical stability and low vapour pressure of ionic liquids4, the adlayer formation process can be studied and the interfacial properties tuned in a significantly larger potential range.In the given presentation, we will focus on the adsorption of 4,4’-bipyridine (4,4’-BP) on single-crystal model electrodes from ionic liquid electrolyte. To gain insight into the process and formed structures, we have combined electrochemical impedance spectroscopy and in situ scanning tunnelling microscopy measurements with density functional theory calculations. The results show the formation of two distinct 4,4’-BP adlayers on the Sb(111) electrode on top of each other, visualized thanks to the occurrence of partial reductive desorption of 4,4’-BP5. In the case of the Cd(0001) surface, a similar reduction process was visible in the cyclic voltammetry and capacitance, potential dependences, although the formed 4,4’-BP adlayers were not visible with the in situ STM. Acknowledgments: This work was supported by the Estonian Research Council grant PSG249, and by the EU through the European Regional Development Fund under project TK141 (2014-2020.4.01.15-0011).