A series of 4-amino-3-hydroxy-naphthalene-1 sulfonic acid derivatives (1–18) was synthesized and tested in vitro for its anti-microbial potential. The results of antimicrobial studies indicated that derivatives having 3,4,5 trimethoxy (6) and 2,4 dichloro (17) groups on benzylidene amino portion were found to be most effective ones. The mt-QSAR model for anti-microbial activity revealed the importance of topological parameter, valence zero-order molecular connectivity index (0 vv ) in describing the antimicrobial activity of synthesized 4-amino-3-hydroxy-naphthalene-1-sulfonic acid derivatives.