Erosion limits the collection efficiency of cyclones and affects their reliability. A new method uses triboelectric probes to measure relative wall erosion rates in cyclones. Reliable measurements can be performed in about 1 min. The erosion rate generally increases with both gas and solid flow rates. However, at high flow rates, a dense protective layer of slowly moving solids forms at the wall, and the erosion rate decreases slightly with further increase in flow rate. The erosion maps indicated that particles rebound on the cyclone wall. Erosion is most severe at the locations where particles rebound.