Comparative studies have been carried out on the electrosynthesis of sodium phosphates in the cathode compartment of an industrial membrane cell supplied with phosphoric acid of concentrations ranging from 1 to 2 mol dm(-)3. The anode compartment of the cell was supplied with brine containing 25% NaCl. Du Pont Nafion(R) membranes of types N-423, N-901 and N-961 were used. It was found that current efficiencies for the production of sodium phosphates exceeded 96%, this being higher than that for sodium hydroxide and, in spite of the different properties of the membranes, these efficiencies were similar. With N-423 membrane, the current efficiency was 2 similar to 3% lower than that for other membranes, but at the same time, the voltage of the cell was lower by 8 similar to 12%. Thus, N-423 membrane gives better performance during sodium phosphate synthesis as compared to membranes N-901 and N-961.