A variety of equations for estimating vapor pressures of organic liquids are available in the literature. Most of the methods involve an extension of the Clausius-Clapeyron equation combined with Pitzer’s three-parameter corresponding states approach [1]. The Lee-Kesler equation [2] is the most commonly used equation for engineering applications and generally predicts vapor pressure to within 1% error between the boiling point and the critical temperature. This error, however, increases rapidly at lower reduced temperatures approaching the melting point. An accurate and generalized vapor pressure correlation for organic liquids valid from the melting to the critical temperature is currently not available. Such a correlation is crucial in the development of accurate liquid state and vapor state equations of state where the knowledge of the coexistence boundary between the two phases is essential