The ionic conductivity of YBa2Cu3Ox has been determined from the Warburg impedance at the lowest end of a full impedance spectrum which was constructed by combining a partial spectrum directly measured by ac impedance spectroscopy and the Fourier-Laplace transform of de relaxation. In the tetragonal. regime, the ionic conductivity has been found to be essentially independent of oxygen partial pressure with an activation energy of 2.46 +/- 0.05 eV. It is also suggested that the conductivity in the orthorhombic regime is Little dependent on oxygen partial pressure but with an activation energy of 1.58 +/- 0.03 eV. The reported data on ionic transport are exhaustively reviewed in comparison with the present result.