The present invention relates to a new method for preparation of biobased imidazolium salts and derivatives thereof; in particular, for the preparation of imidazolium hydrogenooxalate. The present invention also relates to uses of imidazolium hydrogenooxalate salts, especially as a precursor of imidazolium carboxylate compounds. The present invention also refers to a green electrochemical process providing imidazolium compounds, especially imidazolium carboxylate compounds. Especially, the invention refers to a one-compartment electrochemical cell and its use for the preparation of imidazolium carboxylate compounds of formula (II):