Thermal protective coatings find an increasing demand in industry. They are currently used in power generating combustion turbine engines, allowing to rise up significantly the allowing to evaluate the magnitude of a flaws in coated conductor surface from a change in the electrical impedance of an eddy current coil. A theoretical solution is based on the finite difference method (FDM) for the two dimensional vector magnetic potential and electric potential around a coated conductive half space with a long surface breaking crack. The diffusion equation was solved by decomposing the coil field by plane waves and taking into account only the main frequency in the coil spatial frequency spectrum. In order to verify obtained results, experimental modeling was carried out. A set of austenitic stainless steel samples electroplated with 60 and 100 μm tin coatings, containing EDM notches of varying depth from 0 up to 600 μm, was manufactured. The specimens were studied experimentally in the frequency range 100–500 kHz using rectangular shape air core surface coils. Comparison between the experiment and theoretical predictions is given.