This paper presents a numerical method developed for the calculation of the electric field with space charge in electrostatic powder coating with a corona spray gun. An extended commercial computational fluid dynamics (CFD) code was used in the numerical simulation. The free ion charge density was calculated using the conservation equation for the charge density. The time-dependent and inhomogeneous field charging of the particle was applied. Based on the Lagrangian approach, the trajectories of the powder particles were modelled considering electric and aerodynamic forces. The numerical results, such as ion current density distributions, particle charge, static film thicknesses as well as dynamic film thicknesses on the target were compared with the experiment. (C) 2003 Elsevier B.V. All rights reserved.