In 1881, the French physicist d'Arsonval was the first to suggest the harnessing of the temperature difference between the warm surface layers and cold deep layers of tropical oceans. Since then, several attempts have been made to convert this undepletable supply of thermal potential energy into mechanical energy and, later, into electricity. In recent years, various countries including France have launched thermal energy conversion (OTEC) programmes. Tropical regions with useful temperature differences often lack both conventional energy resources and potable water. In such regions, OTEC plants could be used with advantage for the simultaneous production of power and desalinated seawater. An original seawater distillation scheme using surface water and the cold reject stream from an OTEC cycle is discussed. Power not required for distillation may be exported outside the plant. The combined distillation and OTEC scheme is compared with conventional desalination plant producing both potable water and electricity. The OTEC scheme appears highly flexible and shows considerable economic promise.