The adsorption and corrosion protection of 1-pyrrolidinedithiocarbamate (PDTC) and 2,5dimercapto-1,3,4-thiadiazole (DMTD) on bare Pb were investigated. Surface analyses revealed that for high concentration (i.e 10 mM), the organic molecules are strongly adsorbed on Pb surface. In 30 g.L-1 NaCl, Pb corrosion current was highly decreased and anodic passivation was very efficient. EIS measurements and simulations enabled to evaluate organic films thickness, anodic charge transfer resistance Rta and metal/film interface resistivity ρ0. Efficient Pb corrosion protection was confirmed. Results obtained from Young and power law models showed that EIS parameters are not much dependent on the chosen analytical expression.