In this work, a more rigorous model of the vapor phase was considered in characterizing the molecular distillation more realistically. The model used here tries to predict the behavior of the molecular distillation in terms of several factors that, in a considerable way, influence the evaporation efficiency, e.g, design of the molecular distillators in relation to the distance between the evaporator and the condenser and their geometries, pressure of the system, and condensation temperature. This model was developed in the literature by several authors. The objective here is to consider it in the DISMOL software (developed by the authors of this work) taking into account the main contributions available.