The contradiction between the experimental data and theoretical concepts on gasification of disperse carbon in the diffusion flame of hydrocarbon fuels is examined. As a result of the heterogeneous reaction of carbon with molecules of carbon dioxide and water inside a laminar diffusion flame, complete gasification of particles within the time of their residence in the flame is impossible. A hypothesis concerning the two-stage mechanism of in-flame gasification of soot in a sootless diffusion flame is advanced. A mandatory stage is explosive dispersion of disperse carbon particles. The viability of the hypothesis is confirmed by calculated and experimental data.