A simple strategy for covalent immobilizing DNA sequences, based on the formation of stable diazonizedconducting platforms, is described. The electrochemical reduction of 4-nitrobenzenediazonium salt ontoscreen-printed carbon electrodes (SPCE) in aqueous media gives rise to terminal grafted amino groups.The presence of primary aromatic amines allows the formation of diazonium cations capable to react withthe amines present at the DNA capture probe. As a comparison a second strategy based on the binding ofaminated DNA capture probes to the developed diazonized conducting platforms through a crosslinkingagent was also employed. The resulting DNA sensing platforms were characterized by cyclic voltammetry,electrochemical impedance spectroscopy and spectroscopic ellipsometry. The hybridization event withthe complementary sequence was detected using hexaamineruthenium (III) chloride as electrochemicalindicator. Finally, they were applied to the analysis of a 145-bp sequence from the human gene MRP3,reaching a detection limit of 210 pg �L−1.