A monocarboxylic acid derivative of tetrathiafulvalene is Immobilized on RuO2 and PtO electrodes using alkylaminesilane chemistry. The cyclic voltammogram for oxidation of this molecular surface state to the radical cation involves larger surface activity non-Ideality parameters than does that for further oxidation to the dicatlon. Oxidation to the radical cation is facilitated by addition of chloride to the acetonitrile solvent medium. © 1979, American Chemical Society. All rights reserved.