AbstractThis work discusses the kinetics of the hydrogen oxidation reaction (HOR) and hydrogen evolution reaction (HER) on a polycrystalline platinum electrode in acetonitrile, in presence of two different electrolytes. Our findings indicate the sensitivity of the kinetics of these reactions to the presence of small amounts of water. In situ FTIR spectroscopy reveals the ion migration owing to the preferential solvation of protons by residual water, whereas surface‐enhanced Raman spectroscopy confirms that the water leaves the interface under hydrogen oxidation conditions. These observations imply that the kinetic sensitivity of this electrocatalytic reaction towards the preferential solvation processes presents a serious constraint in the establishment of a reference electrode for nonaqueous solvents based on HOR/HER on platinum, and on the comparison of its catalysis in various nonaqueous solvents.