Lysozyme-DNA-aptamer complexes were electrochemically detected at Hg electrodes. Specific and non-specific lysozyme-aptamer complexes were discriminated. Modification with thioglycolic acid promoted adsorption of complexes on the Hg surface. Lysozyme-DNA complexes adsorbed on Hg disintegrated at negative potentials. Constant current chronopotentiometry allows analysis of protein-DNA interactions.