Photocurrent and electrochemical impedance spectroscopy of a polycrystalline semiconductor photoelectrode, Fe2O3 (Ta), was carried out. The analysis of the frequency dispersion of the real and imaginary parts of the complex impedance allowed us to obtain an equivalent circuit for the electrochemical cell. The capacitance of the space-charge layer in the semiconductor electrode was isolated, and the limiting step of the electrode process was determined. Measurements of the temperature dependencies of the electroconductivity were used to determine the activation energy for the mobility of the charge carriers. A pair of simultaneously illuminated n-Fe2O3(Ta) and p-Cu2O photo electrodes were shown to split water spontaneously.