Anion-exchange membrane fuel cells (AEMFC) are promising mainly due to the possibility to use none-PGM catalysts in the alkaline media [1]. However, before elaborating with alternative catalysts a better understanding is needed on which electrode is limiting and what the limitations are for the reference Pt/C catalyst. In fact, the rate constants for the ORR and HOR are not determined in the in the fuel cell [2]. On top of this the influence of water on the kinetics and water transport in and between the electrodes is debated [3]. In this study we have measured the influence of partial pressure in both a symmetrical H2/H2cell a H2/O2cell. Experimental I-V and impedance data has been modelled by two separate physic-based models. The experimental results show that the hydrogen reaction has two separate time-constants in the impedance spectra for the symmetrical cell, indicating a two-step reaction at the anode (see Figure below). From the O2/H2cell the ORR is found to be the limiting reaction at low currents densities, while the HOR has a greater impact at high currents densities. From the model, a limiting current is observed at the anode. The level of humidity is likely not determining the direct catalytic reaction kinetics but may affect indirectly through its impact on ionomer conductivity and swelling. Fig. Nyqvist plots of H2/H2symmetrical cell at OCP at different H2mixtures in Ar at 50°C, 95% RH, 125 ml/min. MEA: 0.4 mg/cm2Pt/C, AS4 ionomer and A201 Tokuyama membrane [4]. [1] D. R. Dekel. Journal of Power Sources, 375:158–169, 2018. [2] E. S. Davydova, S. Mukerjee, F. Jaouen, D. R. Dekel, ACS Catal. 8 , 665-6690, 2018. [3] B. Eriksson, H. Grimler, A. Carlson, H. Ekström, R. Wreland Lindström, G. Lindbergh, C. Lagergren, Int. J. Hydrognen Energy 44, 4930-4939, 2019. [4] A. CarlsonShapturenka, B. Eriksson, G. Lindbergh, C. Lagergren, R. Wreland Lindström, Electrochimica Acta 277 (2018) 151-160