This study establishes a real-size 3D fluid dynamics model of the air-side manifold of an industrial 5-kW proton exchange membrane fuel cell stack containing 67 cells. The calculated flow pattern and pressure drop of the airside manifold agree with experimental observations and measurements. This study evaluates three designs of the inlet manifold and two designs of the outlet manifold. Adding a baffle in the inlet manifold reduces the pressure variation in the inlet air channels from 39% to 2%. A baffle beneath the air stream inlet with a porous baffle on top of the channel creates a highly uniform pressure across the entire air channel. Modifying the outlet manifold or adding a baffle in the outlet manifold does not affect the distribution of the pressure. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.