Interlaminar shear strength (ILSS) of fiber-reinforced polymer (FRP) composites is one of the most important mechanical properties desired by various structural applications. This work has developed a three-phase (consisting of glass fibers, a polymer matrix, and antimony oxide nanoparticles as additional reinforcements) composite material with superior interlaminar shear strength (ILSS) suitable for structural applications. Initially, antimony oxide nanoparticles are synthesised by the solution combustion method using antimony nitrate as fuel and parthenium as an oxidizer. The synthesised antimony oxide nanoparticles were characterised using XRD, SEM, and EDX. Further, the nanoparticles are uniformly dispersed in the diglyceryl ether of bisphenol(DGEBA).A diglycidyl ether of bisphenoland triethylenetetramine (TETA) systems, and the resulting mixture is used along with the glass fibers to develop composite laminates by vacuum bagging. The specimens were cut from the developed composite laminates, and the interlaminar shear (ILSS) tests were conducted. Test specimens cut from unmodified matrix-based laminates are also tested to obtain baseline data. The results showed a significant enhancement in the ILSS of the nano-modified FRP composite