The present research is based on a comparative study of anhydride cured biobased and petroleum-based epoxy network. The effect of epoxidized soybean oil (ESO) bioresin on petroleum-based epoxy (DGEBA) at varying compositions cured with methyl­hexahydrophthalic anhydride (MHHPA) as curing agent and 2-methyl imidazole (2-MI) as the catalyst has been investigated. The tensile strength of virgin epoxy (42.94 MPa) increased to 48.62 MPa with the addition of 20% of ESO. The fracture toughness parameters; critical stress intensity factor (K IC) and critical strain energy release rate revealed enhancement of toughness in the biobased blends. Differential scanning calorimetry studies confirmed an enhancement in the peak temperature and a reduction in the heat of curing in virgin epoxy on incorporation of ESO content. The thermomechanical and fracture morphological properties of virgin epoxy, ESO, and its biobased blends were investigated by thermogravimetric analysis, dynamic mechanical analysis, atomic force microscopy, and scanning electron microscopy, respectively.