A one-dimensional hydrodynamic model for the collapse of a fluidized bed following the instantaneous shut-off of fluidizing air was developed in terms of the sedimentation of a dense system of monodisperse particles. This model is based on the continuity and momentum equations written for the fluid and solid phases. The solution of the problem was formulated in terms of two distinct regions separated by a discontinuity. All hydrodynamic properties in these regions together with the speed of propagation of the discontinuity were calculated analytically. The predicted pressure distribution compares favorably with experimental data from the literature.