The use of perforated metal sheets as engineered gas diffusion layers (GDL) in proton exchange membrane (PEM) fuel cells was investigated. The effect of different thicknesses, perforation diameter, and in-plane diffusion capabilities were analyzed along with freestanding microporous layers in order to improve gas and water transport. Although these structured GDLs are in an early stage of development, they provide baseline performance at lower current densities, and may already have potential for some specific applications. In addition, the design, manufacturing, and modeling processes with predictive capability can be improved due to their simplified nature. (C) 2011 The Electrochemical Society. [DOI: 10.1149/2.017203esl] All rights reserved.