The aim of OLIPO project is to find suitable extraction methods for an important waste of olive oil production, wet olive pomace, in view of reclaiming it as tanning and retanning material, alternative to petroleum origin materials. The total volume of wet olive pomace in Mediterranean countries where olive crops are traditional is about 80% of processed olives and is the result of a two-phase continuous extraction process. Wet olive pomace is rich in polyphenolic compounds, fats, tannins, non-tannins, possible to be extracted, concentrated, chemical processed in view of developing a new tanning product. The use of new renewable materials from oil industry as biobased tanning material for leather industry represents an important step in lowering carbon footprint of both sectors and complies with circular economy principles. The antioxidant and antimicrobial properties of olive oil pomace can be exploited in view of increasing the efficiency of the new product. The paper presents the characterisation of four kinds of wet olive pomace wastes, water and water-organic solvent extracts as tanning materials in order to select the methods for a new tanning material elaboration and testing on leathers in retanning processes.