Abstract: A method of producing a bi-functional electrode for a metal-air battery or fuel cell comprises growing metal oxide nanowires directly on a metal support using a chemical deposition process. Preferably, the chemical process comprises an ammonium evaporation process. The metal support is preferably a porous metal structure, such as a metal mesh or foam. The metal oxide nanowires are formed of any transition metal or mixed transition metal. Preferably, the nanowires comprise cobalt oxide nanowires.