Oxide-alloy interface of Ti6242S Ti-based alloy was investigated by STEM-EELS technique, after oxidation in both N 2-free and synthetic air atmospheres at 650°C for 1000 h. The chemical shift of Ti-L 2,3 edge and its specific fine structure along the oxide-alloy interface were used as fingerprint to distinguish the different compositions of titanium nitrides and oxynitrides. TiN, Ti 2 N and TiN x O y were identified in the sample oxidized in synthetic air at the oxide-alloy interface. Moreover, a decreasing in the oxidation state of Ti oxides was found along with Sn segregation at the oxide-alloy interface for the sample oxidized in N 2-free atmosphere.