A reactive material processing method is developed in this work for fabrication of thin (25-200 mu m) porous metal sheets of sub-micrometer pore sizes. A green sheet is first prepared by tape-casting of metal oxide-loaded slurry. Then, the green sheet is converted into a porous metallic structure through a high-temperature reduction process. Detailed preparation processes and characterization results are delineated with Ni materials as examples. The resulting 50 mu m-thick Ni sheet of about 50% porosity looks like a metal foil, which is strong enough to be self-supported and flexible to bending. The gas permeance and permeability, depending on the sheet thickness and preparation conditions, is ranged from 5.0 x 10(-5) to 4.0 x 10(-4) mol/(m(2) Pa s) and from 1.5 x 10(7) to 8.5 x 10(7) Barrer, respectively. Such porous metal sheets may be used directly as a micro-filtration membrane or serve as an inorganic membrane support platform. This innovation makes it possible to develop thin flat sheet inorganic membranes with surface area packing density similar or comparable to polymeric membrane sheets. (C) 2012 Published by Elsevier B.V.