Abstract: An electrochemical amplification scheme for detecting very small amounts of redox-active molecules is disclosed. The reaction involves “recycling” of oxidized analyte molecules by way of a solution-phase electron exchange reaction with a sacrificial electron donor. The scheme relies heavily upon the action of a selective monolayer coating on the electrode that suppresses direct oxidation of the sacrificial donor but facilitates the oxidation of analyte molecules. The method is particularly useful for detection of hydroxymethylferrocene at a dodecanethiolate-coated gold electrode with ferrocyanide as the sacrificial electron donor.