The paper describes pilot plant experience with techniques with a potential for improving the performance of electrostatic precipitators (ESPs) by using a novel rapping reentrainment collector and flexible steel cable (in place of solid large-diameter discharge electrodes) for both new and retrofit applications. Rapping reentrainment is a major source of particulate emissions from high efficiency ESPs (in some cases over 50% of the particulate mass emitted from the ESP is from rapping reentrainment). Significant improvement in ESP technology could thus be achieved if emissions from rapping reentrainment were reduced. A novel rapping reentrainment collector was evaluated at small pilot plant scale. The collector consisted of a small precharger followed by a very short collector zone. The precharger used was the cooled electrode precharger developed by Denver Research Institute under EPA sponsorship. The precharger puts a very high charge on the reentrained particles. The particles are then collected with high efficiency in the short collector zone. The overall mass collection efficiency of the reentrainment collector was about 85%.