[en] The microstructure of a scale formed on the ATI 718Plus superalloy during oxidation at 850 C for up to 1 000 h in air was characterised using various electron microscopy techniques taking advantage of recent development and capabilities of energy dispersive X-ray spectrometry. The study shows that a protective multilayered Cr₂O₃ scale was formed on this alloy; the outer Cr₂O₃ layer was coarse-grained, while the inner one was fine-grained. Underneath, a thin layer composed of TiNbO₄ as well as an internal oxidation zone that was a dozen or so micrometres thick and consisted of individual Al₂O₃ precipitates had formed. The growth of the Cr₂O₃ layer caused the appearance of a chromium depletion zone, in which the γ^' particles were not observed.