Oxidized porous silicon multilayers can be functional supports for direct solid phase synthesis of peptides and oligonucleotides once properly passivated by chemical procedures. In this work, we have investigated the passivation ability of porous oxidized silicon multilayered structures by two aminosilane compounds, 3-aminopropyltriethoxysilane (APTES) and 3-aminopropyldimethylethoxysilane (APDMES). The hybridization between a 13 bases oligonucleotides, directly synthetized on the aminosilane modified porous oxidized silicon by in situ synthesis, and its complementary sequence, has been monitored by spectroscopic reflectrometry.