We propose an integrated modeling and optimizationfiramework including detailed computational flo id dynamics based models and polymer electrolyte membrane fuel cell (PFMFC) systems. As an illustration, a multidimensional, multiphysics PEMFC model is constructed that accounts for major transport processes in the gas channels and the membrane electrode assembly. The resulting system of highly nonlinear partial diff rential-algebraic equations is,fidl,v discretized using a finite volume method, and the resulting large-scale nonlinear program is linked to a state-of-the-art interior point ()ptl. n? I. 7ation algorithm. The firaniework is used for solving challenging parameter estimation problems resulting.from incorporation of multiple experimental data points. Also, parametric studies are pei.fi)rmed on detailed water transport mechanisms and distribution c hara cte ris tics, and on overall system peifoi-mance. OUJA proposedfiramework provides a robust and fiast solution methodology, and is planned for modeling extensions and addressing other critical issues in PEMFC technology that require large-scale simulations. (c) 2008 American Institute of Chemical Engineers.