AbstractCoupon specimens of TiAl and TiAl–0.2 mass%Zr (TiAl–Zr) were oxidised at 1273 K in O2 of 0.013 Pa for up to 28.8 ks. The oxidised layers were investigated by SEM and TEM equipped with EDS, and characterised by XRD, XPS, AES and EPMA. The oxidised layers formed on both specimens consist mainly of an outer α-Al2O3 scale and an inner Al-depleted layer beneath it, though a few isolated TiO2 (rutile) grains remain in the scale. The Al-depleted layer consists of Ti, Al and O. The thicknesses of the two layers are uneven for TiAl, while they are uniform for TiAl–Zr. TiAl shows breakaway kinetics, which can be correlated with the appearance of TiO2 grains at the interface of the two layers and their subsequent growth into the Al2O3 scale, whereas TiAl–Zr does not. Zr was found enriched in the Al-depleted layer. The length to thickness ratio of the Al-depleted grains is almost unity for TiAl, though it gradually decreases. However, the ratio increases to nearly 1.8 for TiAl–Zr with the progress of oxidation.