The thermal-hydraulic characteristics of a proton exchange membrane fuel cell (PEMFC) are numerically simulated by a simplified two-phase, multi-component flow model. This model consists of continuity, momentum, energy and concentration equations, and appropriate equations to consider the varying flow properties of the gas-liquid two-phase region in a PEMFC. This gas-liquid two-phase characteristic is not considered in most of the previous simulation works. The calculated thermal-hydraulic phenomena of a PEMFC are reasonably presented in this paper, which include the distributions of flow vector, temperature, oxygen concentration, liquid water saturation, and current density, etc. Coupled with the electrochemical reaction equations, current flow model can predict the cell voltage vs current density curves (i.e. performance curves), which are validated by the single-cell tests. The predicted performance curves for a PEMFC agree well with the experimental data. In addition, the positive effect of temperature on the cell performance is also precisely captured by this model. The model presented herein is essentially developed from the thermal-hydraulic point of view and can be considered as a stepping-stone towards a full complete PEMFC simulation model that can help the optima design for the PEMFC and the enhancement of cell efficiency. Copyright (C) 2003 John Wiley Sons, Ltd.