Circulating Fluidized Beds (CFBs) are applied in several processes as combustion, gasification and pyrolysis. The determination of particles velocity and concentration in the downcomer of CFBs allow obtaining the circulating solid mass flow rate, which is an important parameter to CFB operational conditions analysis. This research aims to design, build, install and evaluate an electrical charge sensor to determination of the average velocity of solid particles in a downcomer of a CFB.