A novel bridged nucleicacid (BNA) analogue, 2'-O,4'-C-methyleneoxymethylene bridged nucleicacid (2',4'-BNA(COC)), was synthesized and incorporated into oligonucleotides. The 2',4'-BNA(COC) modified oligonucleotides showed high binding affinity with an RNA complement and significant enzymatic stability against snake venom phosphodiesterase.