Comparative characteristics of the existing criteria for pitting resistance (the formation potential and repassivation potential for pitting and the minimal galvanostatic pitting corrosion potential) and the potential of a salt film formation showed that the latter is more accurately demarcates the ranges of stable and instable passivity has clear thermodynamic meaning. Moreover the potential of a salt film formation enables one to explain the current oscillations which are a typical feature of the pitting corrosion. So it can be used as a criterion in determining the bounds to pitting resistance for stainless steels