Porous platinum layers were synthesized on highly doped n-type porous silicon by immersion plating in HF-containing hexachloroplatinate solutions. Scanning electron microscopy showed that the deposits attained up to 8 μm depth. The achieved platinum deposits have a random pore structure whereas the original porous silicon substrates show an organized honeycomb-like parallel pore array. Electron probe microanalysis measurements showed that the deposits have very good in-depth homogeneity, indicating also that almost all silicon originally presented was etched away by platinum. The electrochemically active surface area of the platinum deposits was determined to be on the order of 80 m2/cm3 by cyclic voltammetry. copyright The Electrochemical Society.