Open‐circuit potential and impedance measurements were performed on Ti, Pt, and Ir oxides. It was found that thepH dependence of the open‐circuit potential of the various oxide electrodes shows a Nernstian behavior and that the response time of the potential to a change in pH for the more conductive oxides on Pt and Ir is comparable to that of the commercial glass pH electrode. Impedance measurements allowed flatband potential determinations on polycrystalline only in highly conductive solutions. In these solutions, the pH dependence of the flatband potential is Nernstian. For less conductive solutions, it was impossible to deduce the exact flatband potential from the intercept of on the V‐axis