The vertical component of solid velocity has been measured in shallow spouted beds by means of an optical fibre, for different geometric factors of the contactor (angle and inlet diameter) and under different experimental conditions (height of the stagnant bed, particle diameter and air velocity). The study has been carried out with glass beads and materials of lower density (high- and low-density polyethylene, polypropylene and extruded and expanded polystyrene) in the spout zone of shallow spouted beds. The calculation of velocity along the axis has been carried out by solving a force balance rising along the spout and the core of the fountain.