The efficiency of green hydrogen production is hindered by the overpotential of the oxygen evolution reaction (OER), and efficient catalysts like NiF-layered double hydroxide (LDH) are needed. This study aims to elucidate the structure of NiF-LDH during OER in operando, in electrolytes containing various alkali cations using X-ray scattering techniques. Initially, the active structure of the catalyst in single alkali cation electrolytes (LiOH, NaOH, CsOH) will be investigated, followed by electrolytes containing mixed cations (e.g., NaOH with LiOH). Through operando X-ray diffraction (XRD) and pair distribution function analysis (PDF), the study aims to determine whether increased intercalation of cations and water leads to an expansion of the interlayer distance or other structural changes within the catalyst layers. This dynamic characterization is essential for understanding the mechanisms guiding electrolyte-electrode optimization.