Cyanate ester resins are a high performance class of compounds. They have excellent mechanical properties, dielectric properties and thermal properties; however, their major drawback is their brittleness. An attempt was made to improve the impact strength of the cyanate ester resin. In the present study a commonly used cyanate resin, bisphenol A dicyanate (BADCy), was modified by the addition of diallyl phthalate (DAP) and was cured with benzoyl peroxide. The properties of the blends such as thermal and mechanical properties were investigated in detail by scanning electron microscope, dynamic mechanical analysis, thermogravimetric analysis, and mechanical measurement. The results indicate that the addition of the appropriate amount of DAP can effectively improve the impact toughness and the flexural strength while sacrificing the thermal properties of the blends. The maximum impact strength and flexural strength were observed on addition of 15 phr DAP content. However, the thermal stability of the blends was found to be lower than that of the unmodified BADCy resin.