This paper proposes a novel fuel cell stack model for system simulation of the cold start operation. The stack model features the option of spatial resolution in two directions and can simulate two-phase effects that are prone to occur during cold start. These effects include: the sorption process in the triple-phase zone between the membrane and the catalyst layer; the condensation, freezing and evaporation in the porous layers; the two-phase flow in the gas channels with a gas liquid slip model. Compared to a OD lumped model, the proposed stack model provides a more detailed view of the onset of freezing and liquid saturation. In a freeze start simulation from -20 degrees C, the Rapid-Warmup-Operation published by Naganuma et al. [1] is applied and demonstrated as an effective way to quickly elevate stack temperature to +5 degrees C within 30 s. The stack model illustrates in detail the physical phenomena in the cold start and can be further integrated into a powertrain model for drive cycle analysis. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.