Air oxidation, vacuum heating and a subsequent oxidation (DT treatment) of Ti–45Al–2Nb–2Mn–1B (at.%) titanium aluminide resulted in several oxide layers and a hard Ti3Al as an interlayer between the substrate and the oxide layers. Surface characterization was carried out using X-Ray Diffraction (XRD), Glow Discharge Spectroscopy (GDS), electron microscopy, microhardness tests, ball-on-disk tests and profilometry.