Kinetics of hydrogen oxidation (HOR) and hydrogen evolution (HER) reactions on nanostructured thin-film (NSTF) ternary Pt0.68Co0.3Mn0.02 catalyst was investigated in a 50-cm(2) polymer electrolyte fuel cell operated in H-2 pump mode with super-saturated feeds, at 45-90 degrees C and 0.7-2.5 atm H-2 partial pressures. The results showed that the HOR and HER are completely reversible, and that both of these reactions can be described by the same Butler-Volmer kinetics with first-order dependence on the H-2 partial pressure. The specific exchange current density for the 2-electron HOR/HER on the NSTF ternary catalyst, derived from the measured polarization curves, is 489 mA.cm(Pt)(-2) at 80 degrees C and 1-atm H-2 partial pressure. The temperature dependence of the exchange current density is consistent with an activation energy of 38.9 kJ.mol(-1). Compared to dispersed Pt/C catalyst with an ultralow 0.003 mg.cm(-2) Pt loading, the HOR kinetics on NSTF catalyst with 0.05-0.10 mg.cm(-2) Pt loading was 60-110% faster on an area-specific basis, but it was slower on a mass basis. The measured HOR/HER kinetics is a function of the state of the catalyst in that the specific exchange current density increased by 460% when the anode catalyst was conditioned with the same protocol normally used for the cathode catalyst. (C) 2013 The Electrochemical Society. [DOT: 10.1149/2.028303jes] All rights reserved.