Title: standard hydrogen electrode
Long Title: IUPAC Gold Book - standard hydrogen electrode
DOI: 10.1351/goldbook.S05917
Status: current

Definition
For solutions in protic solvents, the universal reference electrode for which, under standard conditions, the standard electrode potential ($\ce{H^{+}}$/$\ce{H2}$) is zero at all temperatures. The absolute electrode potential of the hydrogen electrode under standard conditions can be expressed in terms of thermodynamic quantities by applying a suitable Born–Haber cycle, thus: \[E^{\,\unicode{x26ac}}\left(\rm{H}^{+}/\rm{H}_{2}\right)\left(\rm{abs}\right)=\Delta _{\rm{at}}G^{\,\unicode{x26ac}}+\Delta _{\rm{ion}}G^{\,\unicode{x26ac}}+\frac{\alpha _{\rm{H}^{+}}^{\rm{o,S}}}{F}\] where \(\Delta _{\rm{at}}G^{\,\unicode{x26ac}}\) and \(\Delta _{\rm{ion}}G^{\,\unicode{x26ac}}\) are the atomization and ionization Gibbs energies of $\ce{H2}$, \(\alpha _{\rm{H}^{+}}^{\rm{o,S}}\) is the real potential of $\ce{H2}$ in solvent $\ce{S}$ and \(F\) is the Faraday constant. The recommended absolute electrode potential of the hydrogen electrode is: \[E^{\,\unicode{x26ac}}\left(\rm{H}^{+}/\rm{H}_{2}\right)^{\rm{H}_{2}\rm{O}}\left(\rm{abs}\right)=(4.44\pm 0.02)\ \rm{V}\quad \rm{at}\quad 298.15\ \rm{K}\]

Related Terms
- Faraday constant: https://goldbook.iupac.org//terms/view/F02325
- absolute electrode potential: https://goldbook.iupac.org//terms/view/A00022
- ionization: https://goldbook.iupac.org//terms/view/I03183
- protic: https://goldbook.iupac.org//terms/view/P04900
- reference electrode: https://goldbook.iupac.org//terms/view/R05229
- standard electrode potential: https://goldbook.iupac.org//terms/view/S05912

Source
- PAC, 1986, 58, 955. 'The absolute electrode potential: an explanatory note (Recommendations 1986)' on page 957 (https://doi.org/10.1351/pac198658070955)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/S05917/html
- json: https://goldbook.iupac.org/terms/view/S05917/json
- xml: https://goldbook.iupac.org/terms/view/S05917/xml

Citation: Citation: 'standard hydrogen electrode' 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.S05917
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Accessed: 2026-04-21T20:47:52+00:00