This paper reports an experimental study of methane hydrate crystallization. crystallization and dissociation cycles are performed in an isothermal and isobaric pressurised stirred reactor. Both methane gas consumption and methane hydrate particles population size distribution (PSD) (calculated from turbidimetric measurements) are recorded. The influence of pressure, stirring and two kinetic inhibitors (PVP and FXAP) is quantified. The crucial moment of the additive introduction (dissolved before or injected during crystallization) is particularly focused on. Finally, the bases of a kinetic inhibition model are raised, introducing a dead zone for crystal nucleation and growth.