Title: concentration overpotential
Long Title: IUPAC Gold Book - concentration overpotential
DOI: 10.1351/goldbook.C01230
Status: current

Definition
The concentration overpotential of an electrode reaction at a given electrode current density (\(\rm{c.d.}\)) is basically the difference in equilibrium potentials across the diffusion layer. More precisely, it is the potential of a reference electrode (of the same electrode reaction as the working electrode) with the interfacial concentrations which establish themselves at \(\rm{c.d.}\), relative to the potential of a similar reference electrode with the concentrations of the bulk solution. From such a measured potential difference, with \(\rm{c.d.}\) flowing, one needs to subtract the ohmic potential drop prevailing between the two electrodes.

Related Terms
- diffusion layer: https://goldbook.iupac.org//terms/view/D01725
- electrode current density: https://goldbook.iupac.org//terms/view/E01952
- electrode reaction: https://goldbook.iupac.org//terms/view/E01960
- overpotential: https://goldbook.iupac.org//terms/view/O04358
- reference electrode: https://goldbook.iupac.org//terms/view/R05229
- working electrode: https://goldbook.iupac.org//terms/view/W06686

Source
- PAC, 1981, 53, 1827. 'Nomenclature for transport phenomena in electrolytic systems' on page 1838 (https://doi.org/10.1351/pac198153101827)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/C01230/html
- json: https://goldbook.iupac.org/terms/view/C01230/json
- xml: https://goldbook.iupac.org/terms/view/C01230/xml

Citation: Citation: 'concentration overpotential' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.C01230
License: The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) for individual terms.
Collection: If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org .
Disclaimer: The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using.
Accessed: 2026-06-13T13:26:40+00:00