This paper describes a mechanism of electrification of particles in a pneumatic conveying process by both numerical and experimental approaches. A two-dimensional discrete element method (DEM) is used to analyze the particle movement (collision velocity, number of collision, etc.) in a pneumatic conveying process under various operating conditions. By using a simplified model that assumes that the electrification of single particle is proportional to the vertical collision velocity and the number of particle collision against the pipe wall, electrification during the conveying process is numerically computed. The electrification of particles during pneumatic conveying process is practically measured and then compared with the simulated results to confirm the validity of the proposed model. (C) 2003 Elsevier B.V. All rights reserved.