In open-cathode polymer electrolyte fuel cell (PEFC) stacks, a significant temperature rise can exist due to insufficient cooling, especially at higher current densities. To improve stack thermal management while reducing the cost of cooling, we propose a forced air-convection open-cathode fuel cell stack with edge cooling (fins). The impact of the edge cooling is studied via a mathematical model of the three-dimensional two-phase flow and the associated conservation equations of mass, momentum, species, energy, and charge. The model includes the stack, ambient, fan, and fins used for cooling. The model results predict better thermal management and stack performance for the proposed design as compared to the conventional open-cathode stack design, which shows potential for practical applications. Several key design parameters—fin material and fin geometry—are also investigated with regard to the stack performance and thermal management.