Simultaneous coagulation and charging of newly formed titania aerosol by thermal decomposition of titanium tetraisopropoxide (TTIP) is investigated using a discrete-sectional population balance model in two dimensions: article size and charge. The time evolution of particle size distribution and charge distribution is presented for various initial unipolar ion concentrations with and without electrostatic dispersion. Accounting for the electrostatic dispersion, unipolar ions do not affect the average particle size and geometric standard deviation since ions are dissipated so quickly that particles have little opportunity to be charged. On the other hand, when the electrostatic dispersion is suppressed, product titania average diameter, geometric standard deviation and concentration are affected greatly. (C) 2003 Elsevier B.V. All rights reserved.