The k-th power of a graph G, denoted by G k , is a graph with the same set of vertices as G, such that two vertices are adjacent in G k if and only if their distance in G is at most k. The Harary index H is the sum of the reciprocal distances of all pairs of vertices of the underlying graph. Lower and upper bounds on H(G k ) are obtained. A Nordhaus-Gaddum type inequality for H(G k ) is also established.