Waste conversion into valuable chemical products seems to be a good overcoming strategy both for the fossil fuel resources employment and for the current inefficient waste management. The main step related to the production of chemical from waste is its thermochemical conversion via gasification process. Taking into account the variable composition of waste and its high ash amount, among others, the high temperature melting gasifier is the most suitable system for ensuring the required flexibility. Indeed, besides syngas production, this system allows the melting of waste ash fraction in order to produce a vitrified and inert granular material. A simplified transient one-dimensional model of the oxidation zone including melting phenomenon could help in the understanding of process behavior.