Let Γ = (V, E) be a graph of order η with V = {1, 2, 3, …, η} and E ⊆ [V]2. The antiadjacency matrix of Γ is an η × η matrix where the ij-entry is 1 if ij ∉ E and 0 if otherwise. An antiadjacency matrix can be seen as the opposite of the adjacency matrix of graphs. In this paper, we give the spectrum of the antiadjacency matrix of some graph operations, namely, disjoint union of circulant graphs, Cartesian product of cycle graph and complete graph of order two, disjoint union of complete graphs, complement of a graph, and join of graphs.