A dynamic response of large scale PEMFC model has been studied using computational fluid dynamics (CFD) technique. The power density required during dynamic cycle was taken from one of Federal Urban Driving Schedule (FUDS) cycles to enhance an understanding of flow-field design. The transient simulation of 200-cm(2) active area with two different flow-fields showed different response even though those two designs give similar results under steady state operation. Further, the influence of operating condition and flow direction to dynamic performance and distributions were also revealed. The prediction also showed that both operations given in this study can achieve power required from FUDS cycle but automotive condition (cathode dry) shows more non uniform distributions than stationary condition (well humidified condition). Semi counter-flow direction also gives more non-uniform in distributions than co-flow direction under transient operation. (C) 2014 The Electrochemical Society. All rights reserved.