In this work, we present a steady state three-dimensional model architecture that solves for the performance and water movement within a solid plate PEMFC stack. The model captures water movement through layers within the membrane-electrode assembly (MEA), pore-flooding within the unitized electrode assembly (UEA), two-phase flow in the flow channels, heat transport, gas transport, along with detailed electrochemistry. This model architecture allows the capability to simulate both single cell and stack systems and capture effects both within and outside active area. Through simulations of this model we studied the effect of different operating conditions – relative humidity, temperature, and pressure of the gases – and system parameters – membrane thickness, gas channel design, etc. – on water management and steady state performance of the fuel cell. A significant result from these simulations is the prediction of dry out under certain operating conditions, which can be alleviated by using a porous plate flowfield system. Other results from these simulations will also be presented and discussed.