Five main flow regimes in spout-fluidized bed were identified in this study, namely, fixed bed, spout with aeration, spout-fluidization, jet in fluidized bed and slugging, together with their corresponding major frequencies trans- lated from pressure signals. The empirical equation A = aBb, in which A = Fr * /(H ’ / Di) and B= ( F r * /(H ’ / Di) ) (u g t / umf) are re- spectively the spout-geometry and spout-geometry-fluidization dimensionless numbers, was proposed to distinguish these flow regimes. Five main flow regimes in spout-fluidized bed were identified in this study, namely, fixed bed, spout with aeration, spout-fluidization, jet in fluidized bed and slugging, together with their corresponding major frequencies trans- lated from pressure signals. equation A = aBb, in which A = Fr * / (H ’/ Di) and B = (F r * / (H’ / Di)) (ugt / umf) are re- spectively the spout-geometry and spout-geometry -fluidization dimensionless numbers, was proposed to distinguish these flow regimes.