This work presents a model for the UOP hydrogen once through (HOT) Penex process using the Aspen HYSYS petroleum refining module. The model relies on industrial data of process streams that are taken routinely during normal operating hours. Acquired data sets have been tested and screened to ensure data validity for building the model and avoiding erroneous results. A reaction network with 20 reactions and 19 components has been used for the reactors model. The reactors model has been validated using 4 months of industrial plant data. In addition, rigorous tray-to-tray simulation of the isomerate stabilizer has been utilized to match the performance of the plant stabilizer. The model validated has been used for studying the effects of each process variable on plant performance. In addition, the model has been used in optimizing the operating conditions of the process. This optimization showed a potential for notable fuel savings in the process.