The effect of pressure on the flash point (FP) of various fuels (methanol, ethanol, acetone, ethyl acetate, n-hexane, n-octane, benzene, toluene) and their binary mixtures (ethanol-acetone, ethanol-n-octane, methanol-hexane) has been quantified. It has been found that the FP significantly decreases with decreasing pressure. In particular, in going from 1 atm to 0.4 atm, the FP decreases of about 10 °C for all the pure substances investigated. This means that, when dealing with industrial processes operated at pressure lower than 1 atm, the FP present on the material safety data sheet is not conservative since it is measured at 1 atm. A unique equation for evaluating the FP at different pressures starting from the value at atmospheric pressure has been proposed and validated. This equation applies to both pure substances and their binary mixtures, both ideal and non-ideal.