Linear sweep voltammetry data, obtained for hydrogen evolution on a copper electrode were used to estimate the lability of weak monoprotic acids as proton donors. Analysis of differential equations involving diffusion and kinetic terms shows that the total mass transport of proton donors and acceptors does not depend on the kinetics of chemical steps. Their surface concentrations as functions of the electrode potential can be easily obtained by convolution of experimental voltammograms and used in further analysis. The results show that acetic and glycolic acids are sufficiently labile, whereas the dissociation of the carboxylic group in gluconic acid is kinetically inhibited. The zwitterions formed in glycine solutions cannot be regarded as labile proton donors due to the inertness of the protonated amino group. Transforms necessary for constructing linear Tafel plots are discussed. (C) The Author(s) 2018. Published by ECS.