Experimental impedance data previously obtained for various kinds of lacquered tinplate are fitted using two different equivalent electrical circuits, with the aim of assessing the advantages/disadvantages of this procedure for quality control of the material as compared to direct evaluation of the impedance diagrams, It is shown that for screening purposes the same conclusions can be obtained either by fitting or by qualitative analysis of the diagrams. The physical meaning of parameters obtained from the impedance measurements is also discussed. The results are interpreted on the basis that the lacquer is characterized by intact and porous areas which are associated with a capacitance in parallel with the pore resistance in the high frequency range. At lower frequencies other processes occur in series with the resistance of the pores, For short immersion times, the passivation film present on tinplate is detected, whereas for longer immersion times, faradaic processes are detected.