A mathematical model was developed to describe the reduction of soybean oil triglycerides during hydrogenation. The model was derived from reaction and transport mechanisms and formulated into a system of first-order irreversible rate expressions that included terms for temperature, hydrogen pressure, and catalyst concentration. The model parameters were estimated from experimental data, and the model was used to simulate the results of hydrogenation performed over the pressure range of 0.069-6.9 MPa. The model could be extended to include geometrical isomers formed during hydrogenation.