Synchrotron radiation has been used to study in situ the evolution of growth strains in an Al2O3 scale (the so-called TGO or thermally grown oxide) on a model bond-coat alloy (Ni-19.7 Cr-19.2 Al-0.1 Y at.%) as oxide growth proceeds in air at 950–1100°C, and the changes in these strains due to thermal-expansion mismatch as the samples are cooled. Tensile growth stresses develop in the oxide scales during the initial stages of oxidation, a result of initially formed transition aluminas converting to the stable α-Al2O3 form, but large residual compressive stresses are present at room temperature due to thermal-expansion mismatch between the scale and the bond-coat.