First, the error is small at pH-values higher than 12 (see Fig. and associated discussion) and 𝑎 𝐻 2 = 1. Secondly, when the intrinsic i-V (i.e. the B-V equation for the rds) has an odd parity (centrosymmetric), which is approximately the case for the HOR/HER on platinum, the Koutecký-Levich correction produces centrosymmetric i-V curves (Fig. , proof in SI.M8e). This centrosymmetry has been incorrectly used as a criterion of whether mass-transport has been accurately compensated , . For the micropolarization analysis, using the apparent micropolarization exchange current density 𝑖 0,𝑚𝑖𝑐𝑟𝑜,𝑎𝑝𝑝 (Eq. 35a), one can correctly account for the influence of mass transport through Eq. 35b, derived by implicit differentiation of Eq. 34b (derived in SI.M8a-d) and generalized (Eq. 35b). It must be noted that the effect of mass transport limitations on the observed current is independent of the reaction path, and one only needs to consider the overall consumed and produced reactants and products. This is at first counterintuitive, as one would expect only the rds to be relevant. However, all steps are coupled through the activities of their intermediates, a fact that is often forgoten in simplified views of electrochemical kinetics