Pulsed laser deposition is used to deposit thin films of Na superionic conductor (NASICON). The resulting thin films are good ionic conductors with resistivities between 3 x 10(3) and 5 x 10(4) Ohm cm at room temperature depending on the deposition conditions. By depositing these films on Raipore cation-selective membranes, composite membranes can be fabricated. The cumulative current efficiency of these membranes for the production of sodium hydroxide from sodium sulfate using electrolysis is improved by 23%. In addition, the composite membranes presented a higher resistance to fouling by multivalent cations than the polymeric membranes.