The corrosion of two-phase Ni-10Ti and Ni-15Ti in molten (0.62Li, 0.38K)(2)CO3 at 650degreesC under the atmosphere of air has been studied by electrochemical impedance spectroscopy (EIS). The impedance spectra for both Ni-10Ti and Ni-15Ti are composed of a semi-circle at high-frequency port and a line at low-frequency port indicating a diffusion-controlled reaction. The corrosion of the alloys produces an external scale composed of NiO and TiO2, and a wide internal oxidation region. An equivalent circuit representing the features of the corrosion of the alloys was proposed to fit the impedance spectra, and electrochemical parameters in the equivalent circuit were also calculated. (C) 2003 Elsevier Ltd. All rights reserved.