Single- and two-component monolayers of anthraquinone-2,7-disulfonic acid (2,7-AQDS) and 1-chloro-4-hydroxy-anthraquinone (1,4-AQClOH) have been formed by spontaneous adsorption from low pH supporting electrolyte solutions (typically 1.0 M HClO4 in 80:20 H2O:DMF) and examined using cyclic voltammetry. The voltammetric response for the single monolayers is well defined and the concentration dependence of the surface coverage is well described by the Frumkin adsorption isotherm over the concentration range 1-30 mu M for both 2,7-AQDS and 1,4-AQClOH. The saturation coverages (Gamma(sat)) are (6.8 +/- 0.32) x 10(-11) and (1.9 +/- 0.15) x 10(-10) mol cm(-2), respectively, while the adsorption coefficients (beta) are (4.9 +/- 0.25) x 10(4) and (7.5 +/- 0.5) x 104 M-1 Both monolayers show stabilizing lateral interactions. However, the 2,7-AQDS adsorbates interact more strongly with a Frumkin interaction parameter (g) of -1.62 +/- 0.21 being observed compared to -0.21 +/- 0.02 for the 1,4-AQClOH monolayers. Mixed monolayers, formed from simultaneous adsorption of both anthraquinones also show lateral interactions with full widths at half-maximum of 56 +/- 2 mV being observed for both components. Moreover, the formal potentials, saturation coverages, free energies of adsorption, and lateral interaction parameters of both adsorbates differ significantly when the adsorbates are immobilized within two-component rather than single-component monolayers. The relationship between the composition of the deposition solutions and the two-component monolayers suggests that mixed monolayers exist as a single phase in which the adsorbates do not have a preference for being surrounded by their own kind. These stabilizing lateral interactions are consistent with intermolecular hydrogen bonding in which the 2,7-AQDS and 1,4-AQClOH adsorbates act as electron accepters and donors, respectively.