The complex electrical impedance of Na3H(SO4)(2) along the b(m)-axis has been measured from 25 degrees to 316 degrees C in the frequency range 4 kHz-40 MHz. The temperature dependence of the electrical conductivity shows remarkable changes in the temperature range 160 degrees C-260 degrees C. The sample crystal becomes a fast ionic conductor above 260 degrees C. The conduction mechanisms of proton and sodium ions in the different phases are analyzed in detail with respect to the structural features of the sample crystal.