Electrochemical process engineering plays a central role in the storage of electrical energy, e.g. in accumulators, and the conversion of electrical energy into chemical energy, e.g. in hydrogen production. Our research group focuses on the experimental characterization and numerical modelling of key technologies such as alkaline water electrolysis and redox flow batteries. We use established electrochemical methods such as polarization curves, impedance spectra and cyclic voltammograms to comprehensively characterize individual components, full cells and cell stacks. These analyses are supplemented by individually adapted potential measurement probes, which precisely record local potentials and currents. The data obtained in this way is used not only to determine losses in full cells, but also as a basis for validating electrochemical cell models. These validated models are used as robust optimization tools to reliably predict the performance of cell stacks. Additional research aspects include the avoidance and compensation of stray currents in electrochemical systems and the development of electrochemically deposited catalyst layers on electrode substrates to optimize electrode activity.