Single component monolayers of anthraquinone-2,6-disulfonic acid (2,6-AQDS) or anthraquinone-1,5-disulfonic acid (1,5-AQDS) have been formed by equilibrium adsorption from aqueous 1.0 M HClO 4 onto mercury microelectrodes. The adsorption thermodynamics follow the Langmuir isotherm over the concentration range from 2 x 10 -8 M to 8 x 10 -7 M. The same limiting surface coverage, Γ s (1.0 ± 0.08 x 10 -10 mol cm -2 ), and energy parameter, β (5.5 ± 0.7 x 10 6 M -1 ), are observed for both anthraquinones. The cyclic voltammetry of these single component monolayers is nearly ideal, and the potential dependence of the redox composition follows the Nernst equation with the expected theoretical slope. Microsecond time scale chronoamperometry has been used to probe both the rate of heterogeneous electron transfer to the adsorbed anthraquinone moieties and their surface coverages. Binary monolayers have been formed by simultaneous adsorption of both anthraquinones. A plot of the differential capacitance versus the applied potential exhibits a capacitance minimum at the potential of zero charge, -0.300 V. The film capacitance is estimated to be 30 ± 5 μF cm -2 . The surface pK a of the sulfonic acid groups has been estimated as 2.9 ± 0.5 by measuring the interfacial capacitance as the solution pH is systematically varied. The formal potentials of 2,6-AQDS and 1,5-AQDS are almost identical. Therefore, binary monolayers containing both species exhibit only a single voltammetric peak. Under these circumstances, traditional electroanalytical techniques cannot be used to determine the surface coverages of the individual species. However, in short time scale potential step experiments, three single exponential current decays are separated on a microsecond time scale. These decays correspond to double layer charging and heterogeneous electron transfer to the 2,6-AQDS and 1,5-AQDS redox centers, respectively. This kinetic separation of the Faradaic responses allows the surface coverages of the individual components within the monolayer to be determined. Despite their identical formal potentials, the concentrations of the two anthraquinones in solution have been determined by combining information about heterogeneous kinetics and adsorption thermodynamics.