The invention relates to oligonucleotide-oligocation molecules A.sub.iB.sub.jH that can be synthetized via automated phosphoramidite chemistry having oligonucleotides moieties Ai and oligocations moieties Bj, wherein. A.sub.i is an i-mer oligonucleotide residue, with i=5 to 50, where nucleotide A is an oligomer with naturally or non naturally occurring nucleobases and/or pentafuranosyl groups and/or native phosphodiester bonds, for example selected from the group comprising deoxyribo, ribo, locked (LNA) nucleotides as well as their chemical modifications or substitutions such as phosphorothioate, 2'-fluoro, 2'-O-alkyl, or a marker group such as a fluorescent agent, Bj is a j-mer organic oligocation moiety, with j=1 to 50, where B is selected from the group comprising .--HPO.sub.3--R.sup.1--(X--R.sup.2.sub.n).sub.n1--X--R.sup.3--O--, where R.sup.1, R.sup.2n and R.sup.3, identical or different, are lower alkylene, X is NH or NC(NH.sub.2).sub.2, n varies from 1 to 5 and n1=2 to 20, .--HPO.sub.3--R.sup.4--CH(R.sup.5X.sup.1)--R.sup.6--O--, where R.sup.4 is lower alkylene, R.sup.5 and R.sup.6, identical or different, are lower alkylene and X.sup.1 is putrescine, spermidine or spermine residue, .--HPO.sub.3--R.sup.7-(aa).sub.n2-R.sup.8--O--, where R.sup.7 is lower alkylene and R.sup.8 is lower alkylene, serine, a natural aminoalcohol, (aa).sub.n2 is a peptide containing natural aminoacids with cationic side chains, such as Arginine, Lysine, Ornithine, -Histidine, Diaminopropionic acid and n2=2 to 20.