Abstract : A new semi-empirical expression has been developed which predicts the evaporation rates of pure liquid hydrocarbons under a wide range of conditions. A code has been formulated which, using the above results, calculates the evaporation rates of binary mixtures of hydrocarbons. Extension of these results to real fuels is possible by finding the appropriate binary mixture which approximates the fuel. Analyses of the flammable envelopes surrounding pools of pure hydrocarbon and fuels have also been performed.