Carbon aerogels are highly porous structures which show a very low apparent density. They are generally produced by "templating" methods where a 3D structure is used as a template impregnated by carbon/carbon precursor to give the required geometry. Such materials may have applications in composites, noise insulation, vibration damping. Nevertheless carbon aerogels are quite inadequate to well known aerogel applications like separation and liquid/solid filtration because there is a balance to found between speed o filtration (large pores) and efficiency.