The Fe1.99Ti0.01O3-electrolyte interface is investigated using electrochemical impedance spectroscopy. The analysis of the frequency dispersion of the real and imaginary parts of the complex impedance at various electrode potentials allows us to define the equivalent circuit for the electrochemical cell and calculate its associated parameters. The capacitance of the space-charge layer in the semiconductor electrode is isolated, and the limiting step of the electrode process is determined. (C) 2000 Elsevier Science Ltd. All rights reserved.