Electrochemical Impedance Spectroscopy (EIS) was, for the first time, used to estimate the global transverse proton diffusion coefficient, D-H+(EHM), in electrospun hybrid conducting membranes (EHMs). In contrast to conventional impedance spectroscopy, EIS measurements were performed at room temperature with a liquid interface. In this configuration, the measure of the bulk proton transport is influenced by the kinetics of the transfer of proton at the solid/liquid interface. We demonstrated that the use of additives in the process of the membrane impacts the organization of the hydrophilic domains and also the proton transport. The D-H+(EHM) is close to 1.10(-7) cm(2) (+/- 0.1.10(-7) cm2 s(-1)) for the EHMs without additive, whereas it is 4.10(-6) cm2 (+/- 0.4.10(-6) cm(2) s(-1)) for EHMs with additives.