Two rosin-based imide-diacids were synthesized and studied as epoxy curing agents. In comparison, a similar imide-diacid based on trimellitic anhydride was also prepared. The chemical structures were confirmed by (1)H NMR and FT-IR. The curing of a commercial epoxy with these imide-containing diacids was studied by differential scanning calorimetry (DSC). Thermal stability, tensile and dynamic mechanical properties of the cured epoxies were investigated. The results indicate that rosin-based imide-diacids used as curing agents resulted in significantly higher glass transition temperature, tensile and dynamic mechanical properties than the imide-diacid derived from trimellitic anhydride. Rosin acids have a great potential to replace some of current petroleum-based compounds in the synthesis of epoxy curing agents. (C) 2009 Elsevier Ltd. All rights reserved.