Abstract: The invention relates to an electro-chemical cell having an electrolyte comprising water, a halogen other than fluorine, a halide other than fluoride, which is not oxidized by the halogen as a soluble salt, and a stable, saturated, organic nitrile or dinitrile containing from 2 to 5 carbon atoms or a mixture thereof, said electrolyte being composed such as to exist in two phases, a first phase being halogen and nitrile-rich and a second phase being water-rich and containing halide salt, the cell having an inert electrode in the halogen and nitrile-rich phase and an electrode, containing or contacting halogen oxidizable material, in the water-rich phase. The electro-chemical cell of the invention is particularly applicable to systems containing zinc as the halogen oxidizable material.The use of the nitrile-rich phase reduces the degree of reaction between the halogen and the halogen oxidizable material.