A strategy for a comprehensive discrimination between soot and larger carbonaceous particles through numerical approach and particle sizing based on time resolved laser-induced incandescence (TIRE-LII) was investigated in this paper. TIRE-LII technique which is already a powerful tool for soot particle sizing in gaseous flames, was applied to more practical system as spray turbulent flames. Temporal decay of theoretical LII signals were computed for different classes of particles: soot, cenosphere and full carbonaceous sphere called by analogy "pleosphere", pleo- from the Greek pleos, solid. The temporally resolved LII emissions obtained in a heavy fuel oil and in a diesel oil spray flames were compared to theoretical calculations and to sampling results. This first approach showed that it was possible to discriminate the three classes of particle produced during heavy fuel combustion and to size soot particles during the diesel oil combustion. Moreover, it was also possible to obtain a qualitative tendency of the evolution of the relative volume fraction of each class of particle along the flame axis. (C) 2003 Elsevier Science Inc. All rights reserved.