The simultaneous electrodeposition of nickel and hydrogen has been studied in chloride and sulfate solutions and the individual polarization curves determined from efficiency measurements. Nickel polarization has a Tafel slope of 0.10 and is independent of pH and type of anion at constant nickel ion activity. The nickel polarization data can be explained readily in terms of the transfer of a nickel ion from the solution across an unsymmetrical potential energy barrier to the metal phase. The hydrogen overvoltage evaluated during codeposition at constant pH is substantially the same for both chloride and sulfate solutions with a Tafel slope of 0.12. Hydrogen and nickel deposition appear to occur without any appreciable interdependence over the range of conditions involved in the present work.

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