Here, we review part of the work carried out in our laboratories on carbon nanotube functionalization. Both covalent (sidewall derivatization) and non-covalent (using π-π interactions) functionalization have been used to solubilize carbon nanotubes (NTs). The combination of NTs with various electron donors, mainly using the supramolecular approach, led to a new generation of donor-acceptor nanohybrids which can be used for the development of carbon-based photovoltaic cells. Covalent functionalization has been successfully applied for preparation of water soluble nanotubes and further derivatization of the nanotubes with bioactive molecules hold great promise for application in drug, vaccine and gene delivery. Copyright © 2006 John Wiley & So