The report gives results of measurements--to determine the overall mass and fractional collection efficiency of a hot-side electrostatic precipitator (ESP)--across 1 chamber of a 16-chambered ESP. Measurements of fractional efficiency were conducted across the entire ESP. In situ and laboratory resistivity measurements were performed, and voltage-current characteristics of the power supplies were obtained. An engineering analysis was conducted, including an estimate of the specific collecting area required for a cold-side ESP on the same boiler. Results include: (1) voltage waveforms and secondary voltage-current relationships showed characteristics similar to back-corona although fly ash resistivity was 5 x 10 to the 9th power ohm-cm at 350 C (in situ determination); (2) ESP operation was sensitive to resistivity variation in a resistivity region (2 x 10 to the 10th power to 8 x 10 to the 8th power ohm-cm from laboratory determinations) where no sensitivity was expected; (3) overall mass collection efficiency of an isolated chamber was 99.22% for a specific collection area of 52.6 sq m/(cu m/sec), average secondary voltage was 22 kV, and average secondary current density was 40 nA/sq cm; and (4) the turnkey cost of the ESP system was estimated at $34,940,000 ($44/kW) in 1977 dollars.