The unique ability of porous silicon (PS) formation-functionalization method to confine organic molecules in a selected layer of a PS stack was demonstrated in this paper. Two different experiments were carried out to prove the confinement of 1-heptyne in a selected layer of a PS stack. The organic molecule was added to the anodizing solution during the formation of the functionalized layer only, and its covalent bonding to the PS surface was assessed by Fourier transform infrared spectroscopy and energy dispersive X-ray spectroscopy. At first, a stack with an extremely thin sacrificial layer was prepared in order to separate by brittle fracture the functionalized layer from the unfunctionalized one. Further evidences of spatially selective functionalization were obtained by studying a three-layer sample with the organic molecule confined in the central layer. This will allow developing new applications such as PS multichannel sensors and lab-on-chip systems based on PS. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3524478] All rights reserved.