Due to the occurrence of back corona, the separation of particles with high electrical resistivity in electrostatic precipitators (ESPs) is difficult. In this case, the power consumption of the ESPs is significantly increased, and unacceptably high particulate emissions occur. Here, a novel approach for the separation of highly resistive dusts with ESPs is described. The effective electrical resistance of the dust layer can be modified by the use of low-frequency AC voltage, which significantly improves the separation rates. The new method was tested with various highly resistive dusts in a wire-tube ESP.