The electrical properties of the Au/(CH3)(4)NOH . nH(2)O/Au (n = 5, 7.5, 10) system have been studied by impedance spectroscopy at temperatures down to 130 K. One of the studied electrolytes (CH3)(4)NOH . 5H(2)O (TMAOH5) melts congruently, whereas others, (CH3)(4)NOH . 7.5H(2)O (TMAOH7.5) and (CH3)(4)NOH . 10H(2)O (TMAOH10), melt incongruently. The response of the cell Au/TMAOH . nH(2)O/Au is typical for a polycrystalline electrolyte between solid blocking electrodes and it is temperature dependent. Linear, Arrhenius-type temperature dependences of the values of the resistive elements obtained from the best fit equivalent circuits are observed with the slope change at temperatures corresponding to a phase transition of the electrolyte. The corresponding activation energies of the conductivity E(a) are equal to 0.30 eV (alpha-TMAOH5), 0.61 eV (beta-TMAOH5), 0.18 eV (TMAOH7.5) and 0.17 eV (TMAOH10). Tne two latter values are among the smallest observed for solid protonic conductors. At a given temperature, the conductivities of TMAOH hydrates changes in the order TMAOH10 > TMAOH7.5 >> TMAOH5 whereas the order of E(a) values is the opposite : TMAOH10 less than or equal to TMAOH7.5 less than or equal to TMAOH5. The reasons for the observed differences in electrical conductivity of studied hydrates are discussed in terms of their crystallographic structure.