ZrN and TiN thin coatings have been investigated for use on stainless steel for bipolar plates of proton exchange membrane water electrolyzers. Films were deposited by reactive magnetron sputtering using Ar and N2 from metallic Zr and Ti targets on different substrates to perform a deep characterization of their relevant properties. The effect of the deposition parameters, such as N2/Ar ratio, working pressure, or supplied power, has been explored. The structural, electrical, compositional, and optical properties of the films have been investigated by different techniques such as X-ray diffraction, 4-probe van der Pauw resistance, Rutherford backscattering, and optical reflectance and Raman spectroscopies, providing significant information about the films. Finally, after optimization of the preparation parameters to obtain suitable films, the electrochemical behavior of stainless steel coated by different films has been tested. The obtained corrosion current density for a ZrN/TiN/ZrN trilayer on mirror-polished AISI-304 stainless steel evidence their potential as electrodes in bipolar plates of proton exchange membrane electrolyzers.