As a resolution of the well-known hierarchy problem, like supersymmetry the model of extra spatialdimension(s) proposed by N. Arkani-Hamed, S. Dimopoulos and G. Dvali(ADD) in 1998, and byL. Randall and R. Sundrum(RS) in 1999, have generatedconsiderable enthusiasm among the physics community. In this thesis, we have made a phenomenologicalstudy of both of these models. After a briefintroduction of the ADD model and the RS modelin chapter 1 and chapter 2 and a brief review of theexisting phenomenlogical studies in chapter 3, wehave derived the order $kappa DEGREES2$ Feynman rules inthe context...