T.he excess electron conductivity of three commercial sodium-ion conducting beta-alumina solid electrolytes was determined by the permeation technique between 923 and 1073 K. At 1073 K the conductivity referring to the vapour pressure of pure metallic sodium lies between 1.1 and 2.9 X 10(-4) S/CM with the Li2O stabilized material exhibiting the lowest values. The activation energies amount to 1.0...1.1 eV. In equilibrium with pure sodium the materials under investigation are expected to remain within the electrolytic domain up to at least 1450 K.