In last decades, many different compounds have been tested as potential delivery systems of nucleic acids in gene therapy. Compounds subjected for delivery of nucleic acids should be characterized by low toxicity and high ability to form stable complexes with nucleic acids. In practice they should support efficient transfer of therapeutic material (transgene) to the pathological cells. Introduced transgene by interaction with the corresponding cellular genome induce a permanent curative effect. Our previous study indicated, that good transfection properties, have three-dimensional structures formed by self-organized compounds which are structurally similar to the natural lipids. Particularly, new oligomeric amphiphiles, dicationic and tricationic surfactants, seems to be quite promising. The physicochemical properties of these compounds promote their ability to create a stable, biocompatible complexes with dsDNA and siRNA. In this work we present results of structural studies of the complexes formed on the basis of selected novel dicationic or tricationic surfactants with short nucleic acid oligomers (dsDNA and siRNA, 21 bp). These systems were examined by the use of atomic force microscopy (AFM), small angle scattering of synchrotron radiation (SR-SAXS), circular dichroism (CD) and gel electrophoresis. We performed also toxicity tests on HeLa cells. Studies have shown formation of stable systems with the desired biological and chemical properties.