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AES offers high spatial resolution that is useful when analysing cross sections of nitrided steels. To discriminate between different iron nitride compounds in such an analysis, so-called factor analysis (FA) can be applied. This requires acquisition of Auger electron spectra which are associated with either the γ′-Fe4N or the ε-Fe2–3N phases as principal components. In this study, the N KLL and Fe LMM Auger electron spectral lines of γ′-Fe4N and ε-Fe2–3N phases were acquired in great detail from the pure γ′-Fe4N and ε-Fe2–3N phases obtained by gaseous nitriding of pure iron. To this end, two different samples of known composition were analysed. Firstly, Auger electron spectra were recorded from a nitrided layer with large γ′-Fe4N grains (∼30 µm) on top of an iron substrate. Secondly, Auger electron spectra were recorded from an ε-Fe2–3N outer layer (∼6 µm) with 26 at.% N, on a γ′-Fe4N layer (∼4 µm) with 20 at.% N, created on top of an iron substrate. The latter sample was also used for FA. It is shown that principal component analysis of a series of N KLL Auger electron spectra recorded from the iron nitride double layer could be represented by three contributions. These principal components are associated with γ′-Fe4N, ε-Fe2–3N and the background. On the other hand, when a background subtraction was applied to the acquired N KLL Auger electron spectra, it was not possible to discriminate between the two iron nitride phases