For the thermodynamic performance of refrigerants, there exists predictive tools that can be used for working fluid optimization. It would be highly desirable if such a capability could be developed for flammability. The goal of the present project is to develop the capability to predict, from first principles, the burning velocity of pure refrigerants (R32, R125, R134a, R152a, 1234yf, and 1234ze(E)), as well as their blends. Once developed, the predictive models can then be used to understand the effect of individual components of blends on the burning velocity so that guiding principles can be developed for reducing flammability.