Oligonucleotides carrying a peptide nucleic acid (PNA) tail at the 3'-end have been efficiently prepared by an on-line automated synthetic protocol exploiting commercially available Bhoc/Fmoc PNA monomers for the assembly of the PNA tract, followed by a deprotection/reprotection of the base protecting groups. The syntheses of the ODN domain in the chimeras have then been performed by standard methods. The hybridization properties of the synthesized chimeras with complementary DNA fragments have been investigated by thermal denaturation experiments.