Epoxidized soybean oil (ESO) has been considered to be a green alternative to replace petroleum-based substances as a plasticizer for polyvinyl chloride (PVC). ESO is usually produced in a biphasic reaction system, in which hydrogen peroxide reacts with a carboxylic acid in the aqueous phase to generate an organic peracid that migrates to the organic phase and reacts with the soybean oil to produce ESO. The present study includes experimental data obtained in a previous work, to prepare ESO from soybean oil in a 4 h reaction time under different conditions, with single addition of the reactants and in the absence of catalysts. The paper also proposes a more robust model to predict the effects related to the hydrogen peroxide and formic acid amounts, the stirring speed, the thermostatic bath temperature, and the apparent kinematic viscosity of the system. The experimental results were used to fit a kinetic model for this system, including the heat and mass transfer effects and the undesired reactions. Additionally, the model included a satisfactory prediction of the changes in the apparent kinematic viscosity of the system, significantly improving the description of the heat transfer effects.