In the prospect of a large scale deployment of Renewable Energy for electricity production, plasmas will definitively be a major option to get tuneable, high temperature enthalpy sources without direct CO2 emissions. This paper focuses on the direct decomposition of methane for the simultaneous synthesis of hydrogen and high value-added carbon black. After a review of gas phase carbon particle nucleation and growth physico-chemical phenomena, a new original model for the plasma decomposition of methane is presented. The model solves a reactive turbulent flow in a 3D geometry. The nucleation is based on a detailed reaction mechanism and the particle growth is handled by a sectional method. This model opens the way towards a better understanding of carbon particles gas phase nucleation and growth and consequently to a fine control of high value-added carbon black grades. (C) 2017 Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.