Although the relation between carbon structure and reactivity is well-known from thermal and oxidative studies of coal, char, and graphite, the relation for soot remains unstudied. In this article, the dependence of the soot oxidation rate upon the length and curvature of the graphene segments, which depicts the nanostructure, is shown. Reflecting different ratios of edge to basal plane sites or amounts of ring strain imposed by curvature, burnout rates are found to differ by greater than 400% for the soots studied here. Surprisingly, the different soot nanostructures are readily produced by using different fuels and pyrolysis conditions. (C) 2003 The Combustion Institute. All rights reserved.