Abstract: The present application relates to an outer shell for electrolytic cell for molten salt electrolysis preferably an electrolytic cell for production of aluminium, wherein the outer shell is made from concrete.The present application further relates to a method for producing a cathode for molten salt electrolysis where the cathode is built up on a form having outer dimensions and shape corresponding to the inner dimensions and shape of the finished cathode, by successively placing on said form bottom carbon blocks, eventual intermediate carbon blocks, sidewall carbon blocks, busbars, and eventual barrier layer and refractory insulation material layers, whereafter an outer shell made from concrete is cast upon the layers of refractory insulation material.