Electrochemical Impedance Spectroscopy (EIS)was, for the first time, used to estimate the global transverseproton diffusion coefficient, DH+EHM, in electrospun hybridconducting membranes (EHMs). In contrast to conventionalimpedance spectroscopy, EIS measurements were performed atroom temperature with a liquid interface. In this configuration,the measure of the bulk proton transport is influenced by thekinetics of the transfer of proton at the solid/liquid interface.We demonstrated that the use of additives in the process of themembrane impacts the organization of the hydrophilic domainsand also the proton transport. The DH+EHM is close to 1.10−7 cm2s−1 (± 0.1.10−7 cm2 s−1) for the EHMs without additive,whereas it is 4.10−6 cm2 s−1 (± 0.4.10−6 cm2 s−1) for EHMs with additives.