The influence of sulphur atmosphere on conventionally cast (CM) and on electron beam melted (EBM) γ - TiAl RNT650 alloy exposed to a 1% (vol.) H₂S – air atmosphere at 650 °C for 500 h was investigated. The material produced by CM showed a lower mass gain than the EBM material. XRD and TEM/EDS analyses indicated the formation of rutile-TiO₂/(α-Al₂O₃ + rutile-TiO₂)/amorphous-Al₂O₃ sequence of phases. In EBM a coarse crystalline layer rich in aluminium, oxygen and a small amount of sulphur was found. The higher content of sulphur was in the scale bottom intermixed with amorphous alumina.