A (TiNb)(3)(SiAl)C-2 solid solution was designed and synthesized to improve the high-temperature oxidation resistance of Ti-3(SiAl)C-2. After doping with Nb, the oxidation resistance of Ti-3(SiAl)C-2 is improved. Its oxidation kinetics follows parabolic behavior up to 1300 degrees C. The oxide scale formed on (TiNb)(3)(SiAl)C-2 is thinner and smaller in grain size than that on Ti-3(SiAl)C-2 under the same oxidation condition. The beneficial effect of Nb doping on the oxidation resistance of Ti-3(SiAl)C-2 mainly results from the decreased concentration of oxygen vacancies and titanium interstitials in the rutile form of TiO2, and the inhibited generation of excessive voids in the oxide scale.