Abstract: TNM(Ti–43Al–4Nb–1Mo–0.1B) titanium aluminum alloy has low density, excellent mechanical properties at high temperatures, and good deformation ability at high temperatures and is applied as a new-generation aeroengine low-pressure turbine blade material. Its long-term service temperature can reach approximately 750 ℃. In this paper, a TiAl alloy with a nominal composition of Ti–43Al–4Nb–1Mo–0.1B (atom fraction, %) was prepared using the vacuum induction levitation melting method. Oxygenation samples with dimensions of 10 mm×10 mm×5 mm were fabricated using electrical discharge wire cutting. After sandpaper polishing, the surface of the samples was selected for oxidation testing in air at two different temperatures of 700 ℃ and 760 ℃ for nine oxidation time points of 1–200 h using a muffle furnace. A systematic investigation was performed on the oxidation behavior of the TNM alloy at different temperatures and time exposures by characterizing its surface morphology and surface and cross-sectional oxide composition using scanning electron microscopy, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy. Results revealed that at 700 ℃ and 760 ℃, the TNM alloy displays complete oxidation resistance and antioxidation levels and the weight gain rate of the sample at 760 ℃ is 0.1956 g·m⁻²·h⁻¹, which is much higher than that at 700 ℃. At 700 ℃, the TNM alloy initially forms TiO₂ during the early stage of oxidation, followed by a gradual increase in Al₂O₃ until it covers the entire sample. After 200 h of oxidation, the predominant surface oxides on the alloy were Al₂O₃ with small amounts of MoO₂ and MoO₃, which exhibited excellent oxidation resistance. At 760 ℃, the alloy forms unstable oxide compounds of Al and Ti during the initial stage of oxidation, and the growth rate of TiO₂ is faster, destroying the continuous and dense Al₂O₃ layer on the surface and making the matrix more easily oxidized. After 200 h of oxidation, the predominant oxide on the surface is mainly TiO₂ with small amounts of MoO₂, MoO₃, and other molybdenum oxides, with the oxidized surface of the TNM alloy exhibiting a typical multilayer structure of a TiO₂ layer (outermost layer) + an Al₂O₃ layer + a mixed layer (consisting of Ti, O, Nb, Mo) + substrate. Furthermore, the thickness of the oxide layer is significantly greater at 760 ℃ than at 700 ℃.