A two-dimensional steady-state model for a phosphoric acid fuel cell (PAFC) is developed. While most of the published literature deals with one-dimensional models for PAFC, a two-dimensional model is necessitated in cases where the oxygen concentration changes substantially in the flow direction due to depletion of oxygen and back diffusion of product water. The proposed modeling strategy was validated by: (i) testing in one-dimensional mode for verification of the basic parameters through a micro setup known as "unit cell", and (ii) evaluation of the two-dimensional model through an experimental setup of a PAFC stack with four cells. Further, the utility of the model in design and humidity management, and parametric sensitivity studies are presented.