Nb-doped Ti 3 SiC 2 compounds ((Ti 1-x Nb x ) 3 SiC 2 , x=0%, 2%, 5%, 7%, and 10%) as novel interconnect materials of intermediate temperature solid oxide fuel cell (IT-SOFC) were studied in the simulated cathode atmosphere. The long-term oxidation behaviors and area-specific resistance (ASR) of these compounds have been investigated at 800°C up to 700 hours. Among these compounds, (Ti 0.95 Nb 0.05 ) 3 SiC 2 shows the best oxidation resistance and lowest postoxidation ASR (5.6 mΩÁcm 2 after exposure at 800°C in air for 700 hours), endowing it a great promising material in the application as interconnect of IT-SOFC. After oxidation, Nb is mainly doped uniformly into the lattice of rutile-TiO 2 (r-TiO 2 ) grains formed on the tested compounds. Nb doping could decrease the concentrations of both oxygen vacancies and titanium interstitials in r-TiO 2 . As a result, the oxidation rate of (Ti,Nb) 3 SiC 2 decreases remarkably, the structure of the oxide scale changes from a duplex layer of TiO 2 outer layer and TiO 2 +SiO 2 mixture inner layer to a single mixture layer. Nb doping also increases the amount of semifree electrons, causing the significant reduce of the postoxidation ASR of (Ti,Nb) 3 SiC 2 .