Traditional polymer electrolyte membrane fuel cells (PEMFCs) are planar. High cost and low gravimetric and volumetric power densities are two major issues with the planar design. To improve the gravimetric and volumetric power densities of the PEMFCs and to reduce the cost, a novel cylindrical PEMFC design has been developed. The performance of the air-breathing cylindrical PEMFC is found to be superior to a state-of-the-art planar cell in the high current density region. To understand the effect of various design parameters and operating conditions on the performance of the cylindrical PEMFC, two-dimensional, two-phase, steady-state models of the cylindrical cell for both air-breathing and pressurized conditions have been developed in this work. The developed model of the air-breathing cylindrical PEMFC is validated with in-house experimental data. Experiments were conducted with hydrogen on the anode side and air on the cathode side. The cathode catalyst layer is modeled using spherical agglomerate characterization. With the developed model, the effects of various operating and design parameters on the performance of the cell are studied. These studies show that the performance of the cylindrical cell can be further improved by optimizing these parameters. © 2012 American Chemical Society.