The effect of operating conditions (base angle, gas inlet diameter,stagnant bed height, particle diameter, and gas velocity) on longitudinal, and radial profiles of bed voidage has been studied in the spout, annulus, and both the fountain core and periphery of spouted beds, by means of an optical fiber probe. Correlations are proposed for calculation of the local bed voidage in spout and annular zones, along the spout axis and in proximity to the contactor wall.