The effect of the operating conditions (base angle, gas inlet diameter, stagnant bed height, particle diameter, and gas velocity) on spout geometry has been studied in shallow spouted beds by means of an optical fiber probe. The experimental results have been fitted to an empirical equation for calculation of the average spout diameter in shallow spouted beds. The proposed equation takes into account the effect of base angle and gas inlet diameter, which are parameters that have not been previously taken into account in the literature (for deep beds) and have a great importance in the generation of the spout in shallow spouted beds.