The angular pattern of scattered X-ray radiation (1.2-2.5 Angstrom) from flames has been measured and analyzed. The results are compared with calculations on different molecules, such as polyaromatic hydrocarbons, fullerenes and other spherical structures. Measurements have also been performed on soot condensed on a cooling plate inserted inside a flame. Size- and shape-dependent structures are observed in the measured patterns from flames as well Lis soot measurements. The agreement between calculations and measurements allow the determination of characteristic sizes of the different Structures. We have identified aromatic and graphitic structures and features related to sub-nanometer spherical structures. (C) 2004 Elsevier B.V. All rights reserved.