The existence of an outer cracked layer and an inner more structured porous layer has been observed in electrochemically obtained porous silicon when drying procedures are carried out. The changes in the charge transferred to the porous structure during voltammetric oxidation, the interference fringes obtained by Fourier‐transform infrared spectroscopic measurements, and scanning electron microscopy micrographs confirm the existence of this double layer. Also, drying procedures and voltammetric oxidations drastically affect the intensity and wavelength of the peak maximum in the photoluminescence spectrum. The evolution of the luminescent properties is explained by the introduction of nonradiative recombination centers. ©1996 American Institute of Physics.