Ti-10V-3Al-2Fe and Ti-6Al-4V alloys used in aircraft industries were nitrided using a conventional d.c. plasma technique. The effect of nitriding time, temperature and atmosphere were investigated in detail. X-ray diffraction analysis confirm the formation of TiN and Ti2N phases on the nitrided specimens. Load-dependent microhardness measurements combined with microsturctural analysis revealed the unique features of the case-hardened materials. The microhardness after the nitriding treatment was found to be 17.64 GPa (50 g). From the case of depth profile and microstructure (optical microscopy) the thickness of the nitrided layer was estimated to be 20-50 mum. The corrosion rate of the alloys investigated using potentiostatic polarisation method in sulphide environment was found to be lower than in chloride environment. (C) 2002 Elsevier Science B.V. All rights reserved.