In this paper, we obtain the eigenvalues and Laplacian eigenvalues of the unitary addition Cayley graph Gn and its complement. Moreover, we compute the bounds for energy and Laplacian energy for Gn and its complement. In addition, we prove that Gn is hyperenergetic if and only if n is odd other than the prime number and power of 3 or n is even and has at least three distinct prime factors. It is also shown that the complement of Gn is hyperenergetic if and only if n has at least two distinct prime factors and n , 2p