The flame retardancy of polymer composites is another important characteristic that can determine their applicability. The cone calorimeter is a widely used device for predicting the fire behavior of materials. To re-validate the flammability property of the cured thermoset blend from DGEBA epoxy resin and epoxidized corn oil (EPECO50), parameters such as HRR, COP, and SPR were selected, evaluated, and analyzed to reveal the potential of the thermoset blend (EPECO50) to lessen the toxicity and fire hazards of vinyl ester resin. Figure ) confirm that HRR, COP, and SPR agreed that EPECO50 exhibits a significant improvement in its flammability property compared with vinyl ester resin. EPECO50 registered the following results: (1) 794 kW/m 2 (HRR); (2) 1.45 x 10 -2 G/S (COP); and (3) 18.08 x 10 -2 M 2 /S (SPR). For vinyl ester resin, (1) 888.36 kW/m 2 (HRR); (2) 1.89 x 10 -2 G/S (COP); and (3) 26.12 x 10 -2 M 2 /S (SPR). Here, EPECO50 showed 10.59% lower HRR, 23.13% reduced COP, and 30.77% improvement in SPR against vinyl ester resin.