This work employs porous silicon as a gas diffusion layer (GDL) in a micro-fuel cell. Pt catalyst is deposited on the surface of, and inside, the porous silicon by the physical vapor deposition (PVD) method, to improve the porous silicon conductivity. Porous silicon with Pt catalyst replaces traditional GDL, and the Pt metal that remains on the rib is used to form a micro-thermal sensor in a single lithographic process. The GDL was replaced by porous silicon and used in a proton exchange membrane fuel cell (PEMFC. Wet etching is applied to a 500 [mu m thick layer of silicon to yield fuel channels with a depth of 450 mu m and a width of 200 mu m. The pores in the fabricated structure had two diameters, 10 mu m and less than 1 mu m; its thickness was 50 mu m. Accordingly, the GDLs of the fuel cell are fabricated using macro-porous silicon technology. Porous silicon was fabricated by photoelectrochemical porous silicon etching. The topside of the fuel channel was exposed to light from a halogen lamp. The porous structure was fabricated at the bottom of the fuel channel and patterned by anodization. The principles on which the method is based, the details of the fabrication flows, the set-up and the experimental results are all presented. (C) 2007 Elsevier B.V. All rights reserved.