The electrochemical properties and stability of ruthenium mononitride (RuN) thin films were studied. Coatings of RuN were synthesized on electropolished titanium supports by rf-magnetron sputtering. RuN electrodes appear rather stable against dissolution, independently of pH, but show to possess the greatest stability only in alkaline environment. Under hydrogen evolution conditions the films show relevant catalytic properties, comparable with Pt, Pd and Ru/Ir derivatives; a significant coverage by adsorbed reaction intermediates is involved. These electrodes are of potential application in energetics and sensoring.