https://doi.org/10.1351/goldbook.09132
Empirically-evaluated quantity defined by the equation \[{\cal T} = I\tau ^{1/2}/(A c_{B}) = j\tau^{1/2}/c_{\ce{B}}\] where \(I\) is the electric current, \(\tau\) is the transition time, \(A\) is the electrode surface area, \(\ce{B}\) is the bulk concentration of the electroactive substance \(\ce{B}\), and \(j=I/A\) is the current density.
Note: The SI unit of \(\cal T\) is \(\pu{A s^{1/2} mol-1 m}\).