Tantalum nitride (TaNx) coatings deposited by High Power Pulsed Magnetron Sputtering (HPPMS) technology at different N-2-to-Ar ratios; i.e. 0, 0.25, 0.625 and 1, corresponding to different N/Ta atomic ratio in the film, were investigated as suitable candidates to improve SS316L bipolar plates performance and durability for polymer electrolyte membrane fuel cells (PEMFC). The corrosion resistance of TaNx. coatings was evaluated by potentiodynamic and potentiostatic tests carried out under different cathodic potentials (0.8 V-SHE, 1 V-SHE, and 1.4 V-SHE), electrolyte acidities (pH 3 and pH 6) and test durations (5 and 180 min) in order to mimic real fuel cell operation conditions. Corrosion currents observed for all TaNx. coatings were relatively low (1-15 mu A cm(-2)) regardless of N/Ta atomic ratio and applied variable testing parameters. However, considerable differences in Interfacial Contact Resistance (ICR) values were observed after polarization, depending on tested coating material and conditions. The ICR increased with increasing applied potential, electrolyte pH and test duration for the substrate and all TaNx. coatings. Ta coated SS316L exhibited lower ICR (42-82 m Omega cm(2)) values than the uncoated SS316L (47-278 m Omega cm(2)) at potentials higher than 1 V-SHE. A significant rise in ICR was detected for all nitride TaN films after 180 min of polarization at 1.4 V-SHE in pH 3, showing ICR values from 362 to 538 m Omega cm(2), depending on N2-to-Ar ratio. Ta coated SS316L polarized at 0.8 V-SHE showed low ICR values, around 25-37 m Omega) cm(2). Auger electron spectroscopy (AES) was performed before and after polarization to investigate barrier oxide film formation kinetics. AES study revealed the growth of different composition and thickness oxide layers for each TaNx coating, exposing the great importance of coating composition on subsequent type of oxide formation. Barrier oxide layer characteristics have been found to dominate the ICR response of TaNx films after polarization. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.