A new phosphadithiamacrocycle has been synthesized and used as neutral carrier in ion-selective PVC membranes. These membranes have been applied to the development of perchlorate-selective MEMFETs and ISEs. Both devices have shown Nernstian response and a wide working pH range. The response and selectivity found for perchlorate ions is better than those of conventional ClO4- electrodes based on hydrophobic cations as electroactive species. © 1997 Elsevier Science S.A.