In order to investigate the conductivity phenomena below 400 degrees C in high-temperature-type oxide ion conductors of (Bi2O3)(1-x)(Y2O3)(x) and (Bi2O3)(1-x)(Gd2O3)(x), impedance spectra were measured in the frequency range between 20 Hz and 1 MHz. The conductivity relaxation phenomena observed were studied in terms of the electric modulus formula. The relaxation frequencies were found to show Arrhenius-type behavior and the activation energies were in good agreement with those obtained by high temperature electric conductivity.