In this study, the performance of a thermal precipitator of the disk-to-disk type was investigated experimentally and numerically. The prototype precipitator was basically two disks separated via a circular Teflon (R) spacer. The temperatures of the two disks (one at elevated temperature and the other at room temperature) were individually controlled by a silicone heating element and running water at room temperature. Monodisperse particles of sodium chloride and fluorescein sodium were used to investigate the particle collection efficiency of the precipitator when operated under various aerosol flowrates and temperature gradients. Our experimental data showed that the particle collection efficiency of the precipitator remained approximately constant for test particles with diameters smaller than 300 nm and noticeably decreased as the particle diameter increased beyond 300 nm. A numerical model was developed and showed that the calculated particle collection efficiency was in reasonable agreement with experiment observations. Finally, a simple model was developed to estimate the particle collection efficiency of a typical disk-to-disk thermal precipitator. The model indicated that the particle collection efficiency of a disk-to-disk precipitator is a function of cold-disk deposition area, the average thermophoretic velocity, and the aerosol flowrate. This model may be useful in the future design of a thermal precipitator with the similar configurations. (C) 2012 Elsevier Ltd. All rights reserved.