Spouted beds are widely used in many industrial applications for achieving good gas–solid contact/mixing especially for a bed of coarse/nonspherical particles. The stability of the spouted bed is important and critical for certain sensitive applications like coating, blending, catalytic conversion, etc. This paper presents the results of experimental investigations carried out using both two-dimensional and three-dimensional spouted beds to identify various transition velocities and condition to arrive at a stable spouted bed. Standard deviation and power spectral density (PSD) of pressure fluctuation were used to determine the stable operating fluidization/spouting velocity. Zirconia microspheres were used as the spouted bed material and argon, nitrogen, and methane were used as spouting gases. Standard deviation of pressure fluctuation was calculated at minimum spouting velocity and at a velocity corresponding to transition from stable spouting to unstable spouting condition. It is shown that standard d...