Computer-based video imaging techniques were utilized in order to measure the axial and radial components of particle velocity and voidage profiles in the draft tube region of a semi-circular spouted fluid bed coating device. Computer images were obtained using standard RS-170 video signals (30 frames/s) from an image processing board and a CCD variable shutter speed camera. When measuring particle velocities, low shutter speeds of 1-2 ms were utilized. Due to rapid motion of particles, the images obtained were blurred streaks several millimeters in length, The length and direction of streaks were proportional to the magnitude and direction of the projected velocity vector. By using dispersed back lighting, the particle velocity images appeared as light streaks on a dark background. Custom software was written in order to automatically search for and to identify bright streaks and calculate particle velocities. The velocity measurements obtained from the software were compared with data taken with a high speed Kodak video system (1000 frames/s with a 20-mu s strobe). The results were in close agreement. The video images for analysis of voidage measurements were obtained using the same techniques as for the velocity measurements except with a shutter speed of 0.1 ms. The images thus obtained showed the particles to have a dark outer ring with a light center. The search algorithm for identifying particles involved establishing the gray level for nine different locations : eight compass points and a center point. By searching the frame for the presence of particles, and then comparing the gray levels at the circumference and the center of the particle image it was possible to distinguish between in-focus and out-of-focus particles. A comparison of the results using the software with those of standard models made with glass beads, and by visually counting the particles, was in close agreement.