Abstract: The present invention provides a technique for enhancing electrocatalysis in electrochemical systems. Electrochemical impedance spectroscopy is performed for an electrode/electrolyte system at an intermediate frequency. Using an appropriate equivalent circuit model, the corresponding phase-shift can be derived. From this data, the Langmuir absorption isotherm can be created to determine the relation of and transition between overpotentially deposited and underpotentially deposited reactive species. Knowledge of the overpotentially and underpotentially deposited reactive species permits optimal selection of the operating conditions for an electrochemical system.