The overpotential of hydrogen on a liquid gallium electrode has been studied in the equilibrium phases of isobutanol-water-hydrochloric acid systems. According to our investigations, the eta-lg j curves measured in equilibrium aqueous (W) and organic (O) phases practically coincide. This can probably be explained by the fact that the rate of hydrogen evolution in the equilibrium phases studied is determined by the quasi-independence of the structure of W/Ga or O/Ga boundary layers, as well as of the correlation between the psi(O) potential and the acid concentration of the composition of phases.