Аннотация:The adsorption properties of an electrode of iridium oxide (Ti/IrOx) prepared by thermal decomposition were studied in 0.1 M KNO3 solution by potentiometric titration under isoelectric conditions and by recording equilibrium charging curves. Relations between the free surface charge, q, of an oxide electrode and the potential, E, have been obtained for the first time for Ti/IrOx as functions of solution pH, both at different constant values of total charge Q and (in the form of Q vs. E curves) at different constant values of solution pH. It was found that the acid-base properties of the Ti/IrOx electrode strongly depend on the stoichiometry of the active oxide coating, which can be characterized by the value of electrode potential at a particular solution pH. The experimental data were quantitatively interpreted in terms of the thermodynamic theory of reversible electrodes.