This paper describes the development of a novel thermoset based on epoxidized hemp seed oil. The optimization of the hardener (anhydride) and crosslinking accelerator (2-ethylimidazol) concentration as well as the curing parameters are discussed in detail. The optimized material exhibits a bio-based carbon portion of 57.5 wt% and represents an innovative and sustainable substitute for fully petrochemical-based resins in terms of thermal and mechanical performance characteristics. However, also a major challenge with regard to practical applications of (bio-based) thermosets with anhydride curing agent thermosets is identified and addressed: the sensitivity to moisture absorption both during curing and in the fully cured state.