an anode for the electrowinning of aluminium by the electrolysis of alumina in a molten fluoride electrolyte has an electrochemically active integral outside oxide layer obtainable by surface oxidation of a metal alloy which consists of 20 to 60 weight % nickel ; 5 to 15 weight % copper ; 1 . 5 to 5 weight % aluminium ; 0 to 2 weight % in total of one or more rare earth metals , in particular yttrium ; 0 to 2 weight % of further elements , in particular manganese , silicon and carbon ; and the balance being iron . the metal alloy of the anode has a copper / nickel weight ratio in the range of 0 . 1 to 0 . 5 , preferably 0 . 2 to 0 . 3 .