In the present study, a novel method for determining vapor pressure values for the construction of vapor pressure-temperature curves is introduced. These calculations are based on evaporation data, which are obtained from thermogravimetric experiments. The technique as advocated by Price and Hawkins focused on adapting the Langmuir equation for evaporation to obtain vapor pressure values for volatile organic substances. In practice, it was discovered that such calculations produce unrealistic values of the vaporization coefficient, a. Hence, a comparative method, which eliminates the need for the inclusion of this vaporization coefficient factor, is developed in the present study. This method is based on the ratio of the Langmuir equations for a reference material and the sample under investigation. The proposed method also possesses the potential for calculations that will determine the molecular weights for unknown materials.