The present work reports on the preparation of oligonucleotide conjugates via the formation of aromatic oxime linkage. The conjugation consists in the reaction between the oligonucleotide derivatized at 5'-extremity with a benzaldehyde moiety and an aminooxy reporter group. The conjugation was found highly efficient and was extended for the conjugation of phosphorothioate oligonucleotide. In addition, the stability of the so-formed oxime conjugate was investigated.