This study investigates the impact of electrolyte pH on the oxygen evolution reaction (OER) activity of iridium oxide (IrO₂) using a combination of operando optical spectroscopy, X-ray absorption spectroscopy (XAS), and surface-enhanced infrared absorption spectroscopy (SEIRAS). The results show that the active species for OER, Ir²⁺*O, binds stronger in alkaline conditions compared to acidic conditions at low coverage, but repulsive interactions between these species are higher in alkaline electrolytes. These differences are attributed to the higher fraction of water within the cation hydration shell in alkaline electrolytes, which stabilizes oxygenated intermediates and facilitates long-range interactions. Quantitative analysis reveals that while *O intermediates bind more strongly in alkaline electrolytes, the larger repulsive interactions result in a significant weakening of *O binding with increasing coverage, leading to similar energetics of active states in both acidic and alkaline conditions at OER-relevant potentials. The study provides molecular insights into how the interfacial electrolyte structure modulates the binding energetics and interactions of adsorbates, offering new perspectives for enhancing catalytic activity at polarized solid-liquid interfaces.This study investigates the impact of electrolyte pH on the oxygen evolution reaction (OER) activity of iridium oxide (IrO₂) using a combination of operando optical spectroscopy, X-ray absorption spectroscopy (XAS), and surface-enhanced infrared absorption spectroscopy (SEIRAS). The results show that the active species for OER, Ir²⁺*O, binds stronger in alkaline conditions compared to acidic conditions at low coverage, but repulsive interactions between these species are higher in alkaline electrolytes. These differences are attributed to the higher fraction of water within the cation hydration shell in alkaline electrolytes, which stabilizes oxygenated intermediates and facilitates long-range interactions. Quantitative analysis reveals that while *O intermediates bind more strongly in alkaline electrolytes, the larger repulsive interactions result in a significant weakening of *O binding with increasing coverage, leading to similar energetics of active states in both acidic and alkaline conditions at OER-relevant potentials. The study provides molecular insights into how the interfacial electrolyte structure modulates the binding energetics and interactions of adsorbates, offering new perspectives for enhancing catalytic activity at polarized solid-liquid interfaces.