A novel graph quantity, named Hamming energy of a graph HE(G), has been proposed. It is defined as a sum of the absolute values of the eigenvalues of the Hamming matrix. To be used in chemistry, graph quantity should be able to discriminate between different isomers, i.e., it should be sensitive. Therefore, in this paper, we investigate the sensitivity of HE(G), using different sets of isomers. It was found that HE(G) shows exceptional sensitivity compared to graph energy and other eigenvalue-based graph quantities.