Char and soot characterization was performed for samples obtained from beech particles pyrolysis in a drop tube reactor at various temperatures and residence times. Firstly, an experimental study was performed and highlights the variation of char and soot composition and reactivity with operating conditions. A structure ordering with temperature for soot samples was also experimentally put into evidence. These variations are believed to be consequence of structural changes during char thermal annealing and soot formation process, affecting both carbonaceous matrix and mineral matter. Secondly, a semi-empirical model was developed and validated with thermogravimetry experiments. This model was then used for conversion time estimation in conditions representative of an entrained flow reactor, and shows that a complete conversion of char and soot is possible in a few seconds under severe operating conditions. (C) 2013 Elsevier Ltd. All rights reserved.