A new procedure for preparing arrays of microelectrodes based on sonochemical ablation of thin insulating polymer films on electrode surfaces is described. Films are formed through the oxidative electropolymerization of o-phenylenediamine and micron-diameter holes subsequently burned through films by interfacial acoustic cavitation. Electrodes prepared in this way exhibit steady-state currents in quiescent solution and yield lower detection limits than bare electrodes. This preparation procedure has the potential advantage of being scalable to prepare arrays of arbitrary size.