In this work crystallization of organic compounds in silica aerogels is studied. The effect of density and surface properties of silica aerogels on crystallization of a model substance, naphthalene, from supercritical CO2 is investigated. It is shown that the surface properties of aerogels play a significant role in affecting the crystallization process. Loadings up to 55 wt% could be achieved for hydrophilic aerogels whereas hydrophobic aerogels could be loaded with ca. 40 wt% of naphthalene. Naphthalene crystals in the range of 500 nm-2 mm were obtained inside the aerogel matrix depending on the crystallization conditions. The potential of this process as "adsorptive crystallization" is discussed. (c) 2007 Elsevier B.V. All rights reserved.