We have recently shown that the HER activity of polycrystalline Pt decreases with increasing lithium ion (Li + ) concentration. Our theoretical studies suggest that the apparent PtH binding energy decreases with increasing Li + concentration, which can alter the HER kinetics in tune with the hydrogen binding energy hypothesis. Several other studies suggest that the HER activity of Pt decreases from Li + to Cs + in the order LiOH> NaOH > KOH>RbOH> CsOH as Cs + weakens the PtH2O bonds most. Despite extensive studies using different techniques, the pH dependency of HER kinetics on Pt remains an unsolved problem and here, we explore electrolyte-induced structural changes in both bulk and interfacial water with the help of Raman and in situ Shell Isolated Nanoparticles Enhanced Raman Scattering (SHINERS)) studies. Additional evidence of electrolyte-induced changes in the water structure is obtained by using ex situ 1 H NMR, ATR-FTIR, and density functional theory (DFT) based first principles studies.