Abstract: An electrostatic precipitator (10) having a casing (12) defining a precipitation chamber (6) wherein a plurality of discharge electrode subassemblies (32) are disposed alternately between a plurality of collecting electrode plates (20). Each discharge electrode subassembly (32) is comprised of a plurality of individual tubular discharge electrodes (50) extending vertically between support frame members. Each tubular discharge electrode (50) is comprised of a vertically elongated tubular member (54) having an elliptical cross-section disposed with the longer axis of the ellipse perpendicular to the collecting electrode plates and the shorter axis of the ellipse parallel to the collecting electrode plates. A plurality of corona discharge pins (52) are disposed along the length of the discharge electrodes at spaced intervals and extend outwardly from the longitudinal axis of the tubular member (54) at an acute angle preferably in the range of at least 45 degrees to not more than 60 degrees.