The filtration characteristics of a metal fiber filter on dry soot particles have been investigated empirically as a function of the filter pore size and fiber diameter. Six types of metal fiber filters, having various pore sizes and fiber diameters, were examined experimentally, with a focus on the pressure drop, deposited mass, and filtration efficiency. Filtration efficiency was calculated based on the particle number concentration and expressed as a function of the electrical mobility diameter and time. Dry soot particles were generated by a soot generator (mode diameter: 100 nm; total number concentration: 3.48 x 10(10)/cm(3)). The deposition temperature, total flow rate, and deposition time were set to 250 degrees C (equivalent to a particle approach velocity of 1.7 m/s), 29.2 sLPM, and 1 h, respectively. Our results showed that the pressure drop, mass, and particle number concentration-based filtration efficiency exhibited the same tendencies. Specifically, the filter pore size influenced the initial and final filtration efficiencies, while the fiber diameter had a significant effect on the rate of increase of the filtration efficiency. (C) 2014 Elsevier Ltd. All rights reserved.