An hermetic glass-metal seal, for an electrochemical cell, having a metallic central feedthrough as a terminal thereof which is chemically incompatible with the components of said cell. The feedthrough is connected within said cell to a second compatible metallic element for electrical connection to an electrode within said cell. An inert polymeric material is sealed to the glass or outer metal member of the glass-metal seal and is sealed to and encloses the metallic feedthrough within said cell and the connection area between the feedthrough and said second metallic element.