Nano-and ultraporous glass membranes with pore radii of 4.5-150 nm are prepared from sodium borosilicate glasses of various compositions. Structural parameters (structure resistance coefficient, volume porosity, and filtration factor) and electrokinetic characteristics (conductivity, counterion transport numbers, and electrokinetic potential ζ α * ) of membranes are determined at various KCl and NaCl solution concentrations (10 -4 -10 -1 M) in a neutral pH region. The passage from nano-to ultraporous glasses is accompanied by an increase in |ζ α * | values, which is apparently related to a decrease in the thickness of a gel layer due to the removal of ion-permeable secondary silica from pore channels. The comparison of electrokinetic characteristics of glass membranes (counterion transport numbers, efficiency coefficients, and electrokinetic potentials) measured in NaCl and KCl solutions indicates a higher specificity of K + counterions as compared to Na + ions