In this work, a computational model for the simulation of electrostatic precipitators' (ESPs) operation was developed. Special attention has been paid to several parameters that greatly influence the voltage-intensity curve, namely: ion mobility, ion diffusion coefficient and roughness of the electrode. Specifically, a reliable value for ion diffusion coefficient is given. The model proposed takes into account the coupling between gas, electric fields, and particle motion. The model is applied to a 3D geometry and validated against the experimental data reported in the literature. The comparison is made through the V-I characteristic, showing that the computed results reproduce quite faithfully those reported experimentally. Once the model is validated, the theoretical distributions of velocity, electric potential and ionic density are obtained; in addition, the theoretical collection efficiency is obtained as a function of particle diameter. The proposed methodology allows for the complete modeling of ESP and the estimation of their performance and may be a very helpful tool in the development of this type of equipment. (C) 2015 Elsevier B.V. All rights reserved.