The anodic transfer coefficient \(\alpha_{\rm{a}}\) and the cathodic transfer coefficient \(\alpha_{\rm{c}}\) are defined by the following equations: \[\alpha_{\rm{a}} = (RT/F)({\rm{d}}\ln\! j_{\rm{a}}/{\rm{d}}E); \quad \alpha_{\rm{c}} = -(RT/F)({\rm{d}}\ln\!\vert {j_{\rm{c}}} \vert /{\rm{d}}E)\] In these equations, \(j_{\rm{a}}\) and \(j_{\rm{c}}\) are the anodic and cathodic current densities, respectively, corrected for any changes in the reactant concentration at the electrode surface with respect to its bulk value; incidentally, the symbols \(\ln\! j_{\rm{a}}\) and \(\ln\!\vert j_{\rm{c}}\vert\) imply that the argument of the logarithm is of dimension one, obtained by division with the corresponding unit, e.g., \(\ln\! j_{\rm{a}}\) meaning \(\ln(j_{\rm{a}}/\pu{A m^{-2}})\), and similarly for the other quantities \(\vert j_{\rm{c}}\vert\), \(k_{\rm{a}}\) and \(k_{\rm{c}}\). \(E\) is the applied electric potential, \(R\) is the gas constant, \(T\) is the thermodynamic temperature, and \(F\) is the Faraday constant. In practice, \(\alpha_{\rm{a}}\) and \(\alpha_{\rm{c}}\) are defined as the reciprocal of the corresponding Tafel slopes, \({\rm{d}}E/{\rm{d}}\ln\! j_{\rm{a}}\) and \(-{\rm{d}}E/{\rm{d}} \ln\! \vert j_{\rm{c}} \vert\), made dimensionless by the multiplying factor \(RT/F\). Both the transfer coefficient and the Tafel slope are determined at constant temperature and pressure.