A method for determining the volatility of fuel in a fuel storage system which entails: determining that a refueling event has occurred (210) and that the fuel storage system has subsequently been sealed (220); performing a first pressure measurement (230) at a first time after the determining; performing a second pressure measurement (240) at a second time, the second time occurring after the first time; determining a pressure evolution rate (250) from the first pressure measurement at the first time and the second pressure measurement at the second time; and deriving an estimation (260) of the volatility of the fuel from the pressure evolution rate.