The present projects aims at the development of recyclable lignin-based thermosetting polymers as a sustainable alternative for petroleum-based unsaturated polyester resins which are normally not recyclable. While lignin has already been identified as an attractive bio-source, this project will take up a new challenge by using (monomeric) and oligomeric mixtures as novel feedstock for the development of bio-based and recyclable thermosets resins. The monomeric fractions can act as a bio-based reactive diluent and as such the need for intermediate (costly and time-consuming) fractionation is eliminated. The lignin fractions will first be modified upon reaction with glycerol carbonate and in case of further Diels-Alder reaction with furfural to obtain polymerizable synthons. In a next step, these modified lignin fragments will be crosslinked via either a transesterification reaction or a thermo-reversible Diels-Alder click reaction. In a final part of this project, the processability of these lignin-based thermosets will be studied in addition to their materials properties and the potential to recycle the polymer networks. From the very beginning, this project will evaluate the sustainability of the proposed chemical reactions by applying the CHEM21 metrics toolkit. If needed, alternative modification routes will be developed to improve their sustainability.