A metal-air battery includes (a) an anode; (b) a cathode including a metal that reduces oxygen; (c) a housing for the anode and cathode having an air access that allows oxygen to contact the cathode; (d) a separator between the anode and the cathode; and (e) a hydrogen recombination catalyst within the housing. The hydrogen recombination catalyst can include a Pd, Pt, Ru metal or a salt thereof, and CuO.