The incorporation of nanoparticles in various coatings has enhanced coating performances, thus attracting many researchers to explore nanocomposite coatings. In order to synthesize a novel nanocomposite coating, dehydrated castor oil (DCO - biobased non-edible vegetable oil) was epoxidized with performic acid (HCOOOH) and cured with methyltetrahydrophthalic anhydride (MTHPA) in presence of tertiary amine accelerator, 1-methyl imidazole (1-MI) and characterized by FTIR and 1H NMR. Simultaneously, zinc oxide (ZnO) nanoparticles were synthesized by mixing zinc acetate dihydrate (ZnAc2) with oxalic acid dihydrate (Ox2) by precipitation method and then modified organically with (3-glycidyloxypropyl) trimethoxysilane (GPTMS) by sol–gel method which was confirmed by DLS, FTIR, XRD, E-SEM, EDAX, TEM and XPS. These GPTMS-modified ZnO (G-ZnO) nanoparticles were incorporated into EDCO in various concentrations (0–3 wt%) and their mechanical, chemical, thermal and anticorrosion performances were evaluated. All the coatings demonstrated outstanding mechanical and chemical properties (except for alkali resistance) whereas thermal resistance and anticorrosion properties were enhanced with increase in the loading of G-ZnO nanoparticles.