This paper presents the relationship between electric current fluctuation and energy efficiency of a laboratory scale alkaline elec-trolyzer, combined with a novel rectifier system. Electrochemical impedance spectroscopy of the electrolysis cell provides information on the ohmic resistances, the double layer capacity between electrodes and the electrolyte as well as the frequency dependency of these parameters. Thus, it enables the generation of specific current profiles in order to reduce ohmic resistance from polarization as well as bubble evolution. The measurement results show a connection of the energy efficiency on the provided current profiles as well as on the periodical pulse duration. A pulsed current profile, based on the results from the impedance spectroscopy, is able to reduce polarization and bubble resistance losses, while consuming additional electrical energy. (C) 2018 The Electrochemical Society.