A pseudo-homogeneous two-dimensional reactor model was proposed to describe the dynamic and steady-state behaviors of a fixed-bed pilot-plant hydrotreater used for the hydrotreatment of a partially stabilized light-coker naphtha. The model accounted for not only the hydrogenation reactions and the mass and heat transfer in axial and radial directions in the catalyst bed, but also the heat conduction in the thermowell of the reactor. Steady-state experiments were conducted at various operating conditions. Dynamic experiments were performed by inducing dynamic changes in the hydrogen rate and monitoring the temperature transition in the reactor bed. The simulated temperature profiles in the thermowell were in quite good agreement with those observed in the experiments. Simulation results indicated that the temperature difference between the thermowell and the catalyst bed could be as high as 60 K, which, if ignored, might cause significant errors in the interpretation of the pilot-plant data. Dynamic simulations quantitatively predicted the temperature transition over time when the hydrogen rate was suddenly decreased or increased by 8-15%.