The sulphidation and oxidation behaviour of Ar-arc-melted Ti-50Al, Ti-49Al-2Nb, Ti-49Al-2Ag, Ti-48Al-3Ag-5Cr and Ti-52Al-3Ag-5Cr alloys were studied at 1173 K in SO2 atmosphere (100 kPa) and in H2S-H-2 gas mixture (pS(2)=1Pa) up to 39 hrs. Comparison of the influence of the applied sulphidizing atmosphere and addition of the third and fourth alloying element (Nb, Cr, Ag) to binary TiAl alloy on sulphidation and oxidation kinetics, microstructure, composition and growth mechanism of the scales formed on the above alloys were investigated. It was found that sulphidation and oxidation reactions followed a parabolic or para-linear rate laws. Investigations in SO2 revealed that TiAlAg alloy is much less resistible to the exposured atmosphere in comparison with other alloy compositions, caused probably by an Al-Ag liquid phase formation. Investigations in H2S-H-2 show that TiAlAg and TiAlAgCr alloys sulphidize faster than TiAl and TiAlNb alloys due to formation of an Al-Ag liquid phase on the surface of these alloys. A significant influence of Ag, Nb and Cr additions to TiAl alloy on the microstructure and composition of the formed mixed oxide/sulphide (in SO2) and sulphide (in H2S-H-2) scales and alloy surface layers was observed. The scales obtained in both atmospheres were multilayered and heterogenous and these formed in SO2 were composed of TiO2, Al2O3, TiS and Al2S3, while those in H2S-H-2 of Ti3S4, TiS1.5, TiS and Al2S3. Marker experiments using platinum were performed in order to obtain information about the growth mechanism of scales in both atmospheres used.