The hydrodynamics of gas/solids mixtures, e.g. in fluidization and pneumatic conveying, has a distinct effect on the breakage and degradation of powders. Visualization by means of high speed video imaging of these processes enables a better understanding of the mechanics of these processes and verification of the models developed for describing the process. In this paper, the development and use of high speed photography and video imaging and image processing and analysis for the measurement of particle velocities and concentrations, and divergent angles of gas jets in fluidized beds are described. The implications of the observations and measurements on design and control of these processes are indicated.