The present invention relates to a method for production of molten aluminium by electrolysis of an aluminous ore, preferably alumina, in a molten salt mixture, preferably a sodium fluoride--aluminium fluoride-based electrolyte. The invention describes an electrolysis cell for said production of aluminium by use of essentially inert electrodes in a vertical an/or inclined position, where said cell design facilitates separation of aluminium and evolved oxygen gas by providing a gas separation chamber (14) arranged in communication with the electrolysis chamber (22), thus establishing an electrolyte flow between the electrolysis chamber (22) and the gas separation chamber (14).