Spontaneously adsorbed molecular films containing derivatives of the electron donor tetramethylphenylenediamine (TMPD) or the electron acceptor tetracyanoquinodimethane (TCNQ) are formed by exposure of polycrystalline Au to 1 mM solutions of an alkanethiol TMPD reagent or an alkyl disulfide TCNQ species, respectively. Characterization of these redox-active films by cyclic voltammetry establishes the presence of (3.3 +/- 0.3) x 10(-10) mol/cm(2) of redox-active TMPD groups in the case of TMPD films and (2.4 +/- 0.5) x 10(-10) mol/cm(2) of redox-active TCNQ groups in the case of the TCNQ films. These films readily undergo charge-transfer reactions with complementary electron accepters and donors as verified by reflection-absorption infrared spectroscopy and laser desorption mass spectrometry. These films provide convenient approaches for exploiting well-known charge-transfer chemistry in interfacial adhesion measurements and for tailoring the electronic structure of metal-organic interfaces.