The undesired phenomenon of partial or complete defluidizing can occur in industrial applications involving fluidized beds. That could be prevented by increasing the gas velocity, provided an adequate observation of changes in the hydrodynamic of the fluidized bed is detected early enough. Since the value of gas velocity on defluidization of bed is near the gas velocity at minimum fluidization condition, it is very important to use a methodology that can promptly detect the minimum fluidization velocity region, so that shutting down the process can be avoided. The literature shows that the methods to detect the region of such a velocity are limited, and in practice, the traditional method for determination of minimum fluidization velocity (pressure drop across the bed versus superficial gas velocity) is still the most used. In the present work, a methodology is proposed to detect the region where the minimum velocity takes place in a gas-solid fluidized bed, based on the spectral analysis of pressure fluctuation measurements using a Gaussian distribution curve. Results indicate that the method is satisfactory, and it could be used as a more practical indicator of the region where the defluidization phenomenon occurs. (c) 2007 Elsevier B.V. All rights reserved.