Biomass is the largest source of renewable carbon, so there is a rapidly growing interest on its use for production of decarbonized organic compounds, from fuels to specific. Transformation of biomass derivates to valuable products by electrocatalytic methods is a promising technology. However, the technology is still in its relative infancy, and challenges to be tackled span from laboratory development to the necessary scale-up towards industrial use. In particular, understanding processes and study of reaction intermediates requires new efficient in-operando tools. The MEGOPE project wants to deal with those great challenges by setting a new methodology to investigate rapidly and in-operando electrochemical valorisation of complex mixtures. It will give access to a better understanding of the underlying processes involved in molecular electro-reactivity and go a step further into scaling-up to industrial needs. Thus, two kind of instrumentation will be developed: a DEMS coupled to a Chemical Ionization Mass Spectrometer for organic volatile detection, and an innovative new soft ionization source (V-EASI) associated to a MS/MS for rapid identification of intermediates and high mass products, whose development is the core of the project. This methodology will be used first on already studied compounds issued from cellulose transformation (HMF, furfural) and in a second step to less known phenolic compounds issued from lignin decomposition. The final aim of the project is to use the developed methodology to investigate a step further in more complex mixtures, notably fractions issued from lignin valorisation. The MEGOPE project associates two complementary laboratories: ICP (Univ Paris Saclay) whose team is well known for their MS development and IRCELYON (Univ Lyon 1) experts in electrocatalysis and biomass valorisation, in order to bring state of the art instrumentation development to biomass transformation identification.