Carbon gasification is an important reaction in industrial processes, energy generation processes, and diesel soot reduction. The observed kinetics are briefly reviewed, both in non porous and porous materials. The cases of combustion of graphite, coal, char, coke and diesel fuel soot are compared. A review of the proposed mechanisms is done with an emphasis in carbon bulk diffusion, using Fick's Law to articulate the carbon bulk diffusion step with the other steps. The relevance of the Hedvall effect and the Tammann temperature in transition metals is addressed, including a discussion about the relation between mechanistic models and phenomenological models.