Abstract : Boron nitride nanotubes are new tubular materials which are structurally related to carbon nanotubes and are made of one or several rolled-up hexagonal boron nitride sheets. Nanoelectronics, material science and medicine are among the potential application fields of these tubular structures. Single-walled boron nitride nanotubes (SWBNNTs) are being produced by continuous LASER ablation at the ONERA. The crude samples contain SWBNNTs and boron nitride cages but are also contaminated by boric acid and hexagonal boron nitride fragments. A purification method of these samples has been developed in order to get on one hand nanotube-enriched samples and on the other hand boron nitride cages. The process includes multiple cycles of sonication, centrifugation and filtration and has been shown to be efficient for different types of boron nitride nanotubes samples.Thanks to the presence of boron and nitrogen atoms that promise better reactivity than carbon, boron nitride nanotubes are expected to be good candidates for chemical functionalization. In addition, most of the foreseen applications require their dispersibility and compatibility with different solvents. Exohedral chemical functionalization of boron nitride nanostructures allows, as for carbon nanotubes, their suspension and solubilization in either aqueous or organic conditions. New methods of functionalization have been developed and applied to boron nitride cages, multi-walled and single-walled boron nitride nanotubes samples. Two different methods involve either strong interactions with the boron electron vacancy or stacking of a borazinic cycle on the boron nitride network. The efficiency of functionalization is demonstrated by macroscopic solubilization of the samples in aqueous and organic solvents and transmission electron microscopy studies. The reversibility of this fonctionalization can be proven by dialysis against the corresponding solvent. The second part of this work deals with separating carbon nanotubes by electronic or morphology properties. Two different methods of separation of carbon nanotubes are being envisaged. The first one involves microwave irradiation of carbon nanotubes samples and leads to size separation of the nanotubes. The second one involves specific interactions of fullerene micelles with one type of tubes. Synthesis difficulties did not allow us to interact functionalized fullerenes with carbon nanotubes to try to induce selectivity.