Investigations have been carried out to probe the interactions between double stranded DNA and non-amphiphilic chromium(III) complexes. [Cr(en)(3)](3-) and [Cr(phen)(3)](3+) (en-ethylenediamine, phen-1,10 phenanthroline) in mixed monolayers with dihexadecyl phosphate (DHP). Under the experimental conditions, the results show that there is a specific binding mode between [Cr(en)(3)](3+) and DNA at air/water interface based on adsorption followed by a strong binding of [Cr(en)(3)](3-) to DNA based on H-bonding. In case of [Cr(phen)(3)](3+). the results indicate that after initial adsorption of DNA to the metal complex. partial intercalation of Cr(phen)(3)(3+) takes place in the strands of DNA. (C) 2002 Elsevier Science B.V. All rights reserved.