In this work, the method of electrochemical impedance spectroscopy is applied on six different high impedance coatings using two electrochemical cells of different construction, of which one is more suitable for laboratory usage, whereas the other one for measurements in situ. The given results from two experimental and two computational strategies are processed statistically and mutually compared. Numeric values of electrical properties of coatings were given by direct reading of the impedance on 0.1 Hz and the capacitance on 100 Hz for both cells, and by mathematical modeling for the big cell. The impedance results for the small cell differ from the ones in the big one in greater dissipation of measured points in low frequency range, which in turn makes results modeling of the small cell impedance results impossible. There is an excellent correlation of modulated capacitances and the directly read capacitances for the big cell (r^2=0.997), and the correlation is lower for the small cell (r^2=0.834). Modelled impedances are higher than the ones directly read because they represent the extrapolation of the electrode behavior in the DC range. If the evaluation coating criteria is applied based on 0.1 Hz impedance, all tested coatings have excellent protective properties (> 1 GΩ cm^2), and by both cells the worst coating, the dark grey one (≈ 9 and 6 GΩ cm^2), and the best coating, the white one (≈ 153 and 59 GΩ cm^2) can be distinguished. The efficiency of protective coatings having impedance within the same order of magnitude is impossible to do for certain. However, because of the evaluation coating criteria which for individual rating spreads within 1.5 up to 2 order of magnitude, it can be concluded that applying the small cell provides acceptable results for measurements on objects in situ.