Abstract: Copper (II) complexes of Diphenyl (2-hydroxyphenyl)(phenylamino) methylphos- phonate (DHPP) and Diphenyl (4-aminophenylamino)(2-hydroxyphenyl)methyl phosphonate (DAHP) were prepared and characterized by different tools such as elemental analysis, IR, 1H-NMR, UV/Vis spectra and thermal studies. The IR spectral data showed that the phosphonate compounds behave as bidentate ligands coordinating to the copper ion through the P=O and NH groups. The geometry around copper ion was found to be a distorted octahedral. The activity of the phosphonate ligands and their copper (II) complexes towards DNA cleavage were investigated. The phosphonate ligands showed no activity, while the copper complexes showed DNA cleavage activity. The copper complex of Diphenyl (4-aminophenylamino)(2-hydroxyphenyl)methyl phosphonate showed strong activity towards DNA cleavage.