Oxidation and reduction of cytochrome c in solution through 11 different self-assembled monolayers (SAMs) on gold electrodes was investigated with cyclic voltammetry. Electron-transfer rate constants of cytochrome c through the 11 SAMs ranged from less than or equal to10(-4) to similar to10(-1) cm/s. A strong correlation between the electron transfer rate constants and the hydrogen bonding ability of the SAM is identified. This correlation is discussed in terms of the dependence of the rate constant on the outer-sphere reorganization energy, the double layer, and the electronic coupling between the cytochrome and the differently terminated monolayer films.