Cashew Nut Shell Liquid (CNSL) is a non-edible natural oil obtained as a by-product of the Anacardium Occidentale nut. Its main component (cardanol) is characterized by a favorable sustainability profile (LCA) and unique chemical features (presence of an aromatic ring, phenoxy groups, and alkenyl side chain), that allow its industrial use in a wide range of thermosetting materials, from alkyds to polyurethanes. When used in epoxy formulations, cardanol-derivatives impart improved hydrophobicity and excellent flexibility to final cured matrices. This paper describes the properties of a novel cardanol-di-functional epoxy compound characterized by high bio-content and low viscosity, comparing its excellent dilution power, and balanced thermal and mechanical properties with the performances of conventional fossil- and bio-based epoxy-diluents and modifiers.