Abstract Reaction order and activation energy for H 2 oxidation on Ni/3 mol.% Y 2O 3–ZrO 2 (Ni/Y-TZP) cermet electrodes have been evaluated by galvanostatic current interruption (GCI) and electrochemical impedance spectroscopy (EIS) techniques. GCI data show a reaction order in P H 2O of 0.4 and activation energy of 76 kJ mol −1. In contrast, a first order with respect to P H 2O and an activation energy of 169 kJ mol −1 are obtained from EIS data. During GCI measurements, the actual H 2O content or P H 2O / P H 2 ratio at the electrode/electrolyte interface region could be significantly higher than that in the bulk electrode as H 2O, the product of the reaction, remains in the gas phase. On the other hand, the H 2O content at the interface region is very close to that in the bulk during EIS measurements under open circuit. It has been shown that H 2O produced at the interface region during GCI measurements enhances the H 2 oxidation reaction, resulting in the shifting of the reaction rate dependency on H 2O and activation energy to lower values as compared to those measured by EIS.