Platinum-coated chromium nitride electrodes are deposited onto gas diffusion layers by normal and glancing angle deposition and are tested as cathodes for proton exchange membrane (PEM) fuel cells. X-ray diffraction and scanning electron microscopy show that the CrN forms 111-oriented nanoparticles with {100} facets that are covered by 3.4 x 10(11) Pt mounds/cm(2), independent of Pt loading 0.05 to 0.25 mg/cm(2). Polarization curves exhibit dE/d(log i) slopes b approximate to -100 and -150 mV/dec for high (E > 0.75 V) and low (E < 0.5 V) potentials, respectively, but show an anomalous drop with b approximate to -420 mV/dec in the intermediate voltage range. This is attributed to poor proton conduction associated with a reversible dewetting of electrode pores during low current operation. Quantitative analyses of rate-dependent polarization curves and electrochemical impedance spectra show that the time scale for pore filling by process water is 10(3) s, and that the ionic resistance R-C within the electrode increases by a factor of 4, from R-C approximate to 0.2 to 0.8 Omega cm(2), as E increases from 0.5 to 0.8 V. The increasing electrode resistance is attributed to a low water production rate at low current, which allows the relatively hydrophobic CrN to expel water from the electrode pores, resulting in a higher resistance for ionic transport. These results show that even ultrathin sputtered catalyst layers can exhibit incomplete flooding. (C) 2009 The Electrochemical Society. [DOI:10.1149/1.3247351] All rights reserved.