This paper deals with nonlinear dynamic modeling of the Proton Exchange Membrane Fuel Cell (PEMFC) dedicated for automotive applications. A time-variant state space model taking into account most of internal phenomena is built. Based on electrical and diffusion approaches, the model proposes a more complete equivalent circuit including all cell components. The proposed circuit couple between gas diffusion, membrane water content, temperature, activation, ohmic and concentration losses, as well as double layer and geometrical capacitances. Similarly to engine vehicles, the model consider the hydrogen flow rate as input controlled by the pilot to change vehicle's speed. Urban and highway driving cycles similar to those of Nissan LEAF are simulated. Simulation results show that the model responds to both low and high dynamics of power demand. Results reveal that membrane humidity has a considerable effect on the cell's efficiency. This offer the opportunity to use the model, in a future work, to improve the fuel cell's efficiency through the control of humidity. The model is validated by experimental tests on a 50 W PEMFC. (C) 2014 Elsevier B.V. All rights reserved.