A bench-scale pulse-energized electrostatic precipitator (ESP) was developed to study the capture of particles from exhaust gas streams from iron and steel factories. The morpho-structural characteristics, composition and size distribution of the particles were analyzed. The results showed that the particles consisted primarily of iron oxides and other compounds containing Ca, S, C, Si, Al, and Na elements. The particles had a broad size distribution ranging from 5 nm to several micrometers. The V-I characteristics of the ESP were studied with biased DC voltages of ± 10 kV and ± 10 kV with superimposed pulses (± 5.5 kV, rise time 60 ns, repetition rate 50 pps). The capture efficiency was investigated by means of a low pressure impactor and scanning mobility particle sizer. In the range of 155 to 6,650 nm, the ESP number-based capture efficiencies were > 99.6% and > 98.9% for negative and positive voltages, respectively. For sizes less than 50 nm, the negative pulsed mode was remarkably efficient (93.7 to 99.4%).