A novel electrochemically induced cis-to-trans isomerization process involving amphiphilic azobenzene derivatives in Langmuir-Blodgett monolayer films at electrode/electrolyte interfaces was examined using electrochemical and UV-visible absorption measurements. This isomerization proceeds electrostatically, i.e., with no Faradaic current and no discernible features in the double-layer capacitive charging current, when relatively positive electrode potentials are applied to the monolayer film. This electrostatically induced process is rather slow (first-order rate constants in the 10(-2)-10(-1) s(-1) range over the potential range of +0.65 to +0.85 V vs Ag/AgCl, respectively), but the highest rate constant measured (at +0.85 V vs Ag/AgCl) represents an increase of approximately 3 orders of magnitude compared to that of the thermal isomerization process. Surprisingly, the activation energy for the electrostatic process was found to be essentially potential independent and nearly the same as that fur thermal isomerization. The rate constants for the cis-to-trans isomerization obtained at given potentials were also found to depend sensitively on details of the molecular structure, such as the length of the alkyl chain connecting the carboxyl group to the azo group (spacer) and the length of the alkyl tail, which implies that the isomerization reaction involves an interaction between the intrinsic electric field of the molecules in the highly ordered film and the relatively strong electric field associated with the electrical double layer at the electrode surface.