Understanding gas hydrate formation and disassociation processes are crucial to managing their risks or utilizing this technology for different applications. Conducting an experiment under all conditions are impractical, costly, and time-consuming. Therefore, it is more practical to use models that could predict all required parameters. In the present chapter, a basic review of the thermodynamic and kinetic models is given. The models are classified based on their mechanisms. The fundamental equations have been highlighted alongside with their possible application models for each chemical.