The application of titanium aluminide orthorhombic alloys (O-phase alloys) as potential materials in aircraft and jet engines was limited by their poor oxidation resistance at high temperature. The Ti2AlNb-based alloys were chromised (Cr), chromium-tungstened (Cr-W) and nickel-chromised (Ni-Cr) by the double glow plasma surface alloying process to improve their high temperature oxidation resistance. The discontinuous oxidative behavior of Cr, Cr-W and Ni-Cr alloyed layers on Ti2AlNb-based alloy at 1093K was explored in this study. After exposing at 1093 K, the TiO2 layer was formed on the bare alloy and accompanied by the occurrence of crack, which promoted oxidation rate. The oxidation behavior of Ti2AlNb-based alloys was improved by surface alloying due to the formation of protective Al2O3 scale or continuous and dense NiCr2O4 film. The Ni-Cr alloyed layer presented the best high-temperature oxidation resistance among three alloyed layers. (C) 2010 Elsevier B.V. All rights reserved.