One of the most modern methods of characterizing the electrical properties of coatings is by electrochemical impedance spectroscopy (ELS). EIS can provide useful information about the transport of water and corrosive species through a coating. In this study, impedance measurements were performed in different frequency ranges at open circuit potential for an alkyd coating with TiO2 as a mineral pigment in 3% NaCl. The most probable impedance equivalent circuit method (MPI) was considered for data analysis. The interpretation of the impedance spectra permitted the determination of water permeation, the formation of blisters, swelling of the coating, and the loss of adhesion.