A method for the synthesis of chimeric oligodeoxynucleotides comprised of phosphodiester and phenylphosphonate [3'-O-P(= O)(C6H5)-O-5'] or phenylphosphono-thioate [3'-O-P(= S)(C6H5)-O-5'] linkages has been developed. Synthesis was performed using suitably protected nucleoside phenylphosphonamidites as building blocks following an adjusted solid-phase phosphoramidite synthesis protocol. The new oligodeoxy-nucleotide analogues were characterized by electrospray ionization- and matrix-assisted laser desorption mass spectrometry, as well as by 31P NMR spectroscopy. Additionally, their binding properties to complementary oligodeoxynucleotides has been studied.