Abstract: A composite membrane is disclosed fabricated by depositing an inorganic ion-conducting thin film on a cation-selective organic polymer membrane substrate using Pulse Laser Deposition (PLD) or reactive magnetron sputtering. The fabricated membrane combines the advantages of the polymeric membrane including flexibility and low electrical resistance, with the advantages of the inorganic membrane film including resistance to fouling, high selectivity for alkali metal ions over hydrogen ions and resistance to oxidizing chemicals; electromembrane systems and processes for example alkali metal sensing electrodes and other membrane-based electrochemical detectors, electrolytic and electrodialytic systems incorporate such membranes thus improving their performance in terms of current efficiency, salt to acid conversion ratio, reliable operation and membrane life.