<p>This paper presents a simulation and performance analysis of a heavy-naphtha hydrotreating unit at Basrah Refinery in Aspen HYSYS with real industrial operating data. The model includes specific feed characterization, reactor kinetics of hydrodesulfurization (HDS) and hydrodenitrogenation (HDN), and proper models of separation and hydrogen recycle systems. Comparison with plant data indicates a high level of agreement (<i>R</i>² = 0.9994) confirming the capability of the developed model to reproduce the measured outlet composition at the investigated industrial steady state operating condition. The performance of the hydrotreating was assessed using a systematic sensitivity analysis to determine how temperature, pressure, and hydrogen mass flowrate impacted the performance. It was found that temperature and pressure have strong effects on impurity removal only at certain operating ranges where it becomes less effective due to kinetic saturation and refractory properties of the sulfur and nitrogen containing species that remain. The greatest effect was found in H₂ mass flow rate, which resulted in steady decreases in H₂S and NH₃, and excess hydrogen in the effluent. Lastly, Aspen HYSYS was used to find an operating window that could be implemented to enhance desulfurization within real refinery conditions, through constrained multi-variable optimization by the use of SQP algorithm, the optimized conditions reduced the outlet H₂S concentration from 7.9 × 10⁻⁵ to 4.27 × 10⁻⁵&#xa0;wt%. In general, the validated model offers a useful decision support system to diagnose the performance and optimize the operations in heavy naphtha hydrotreatment in the industry.</p> Graphical Abstract <p></p>