Abstract: A rechargeable electrochemical cell comprising a positive electrode, a negative electrode and an electrolyte, the positive electrode being such that it is a composition of an alkali or alkaline earth salt of a sulphur oxy-acid and a transition metal oxide, and the electrolyte being such that it is a non-aqueous electrolyte containing a soluble salt of the alkali or alkaline earth metal dissolved in the non-aqueous electrolyte.