The Hiden Differential Electrochemical Mass Spectrometry (DEMS) is an analytical technique that combines electrochemical half-cell experimentation with mass spectrometry. It allows in situ mass resolved determination of gaseous or volatile electrochemical reactants, reaction intermediates and products in real time. Hiden Analytical offer a range of DEMS cells with electrolyte/nanoporous sampling interface to the Hiden HPR-40 DSA Mass Spectrometer.