Hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) of middle distillates over a commercial Ni-Mo/gamma-Al2O3 has been studied under wide operating conditions of 340-380 degrees C and 38-98 atm. A power law model was presented to each one of those reactions. The parameters of kinetic equations were estimated solving the ordinary differential equations by the fourth order Runge-Kutta-Gill algorithm and Marquardt method for searching of kinetic parameters (kinetic constants as well as the orders of the reactions). An adiabatic diesel hydrotreating trickle-bed reactor packed with the same catalyst was simulated numerically in order to check up the behavior of this specific reaction system. One-dimensional pseudo-homogeneous model was used in this work. For each feed, the mass and energy balance equations were integrated along the length of the catalytic bed using the fourth Runge-Kutta-Gill method. The performance of two industrial reactors was checked. Alternative configurations are proposed in this work, which have advantages compared with conventional HDT commercial reactors.