The structural properties of high porosity nanoporous silicon were researched with the manufacture of integrated nano‐explosive devices in mind. A three‐dimensional nanoporous layer structural model, consisting of cylindrical crystallites, is proposed. Model parameters are derived from gravimetric techniques and the electrochemical etching of high porosity nanoporous silicon layers. A gravimetric experimental technique is described whereby the pore dimensions and specific surface area of nanoporous regions can be determined. An inverse relationship between pore size and specific surface area is found, with a constant specific surface area times pore diameter product. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)