The interaction of a structurally characterized Sr-Fe nitrosyl complex with DNA has been studied by UV-vis and fluorescence spectroscopy, viscometric, and gel electrophoresis techniques. From the absorption titration studies the intrinsic binding constant of the complex with DNA was calculated to be 1.6x10(4)M(-1). Fluorimetric studies indicate that the complex compete with EB in binding to DNA. The complex shows nuclease activity on pUC19 supercoiled DNA in presence of H(2)O(2).