The hydrodynamic characteristics of polyethylene resins are studied in detail through a combination of different techniques in our laboratory. Computer Assisted Tomography is used to determine voidage distribution under different operating conditions. Radioactive particle tracking is used to determine the solid particle trajectories, the horizontal and vertical velocities of the solids and the residence time distribution of the solids. X-ray fluoroscopy is used to determine bubble frequency and velocity. All these techniques are then combined with the information obtained through monitoring pressure fluctuations in the fluidized bed columns. All experiments are performed in Plexiglas columns of diameters that vary between 10 and 30 cm in diameter. The materials used are polyethylene and air, respectively. The combination of these techniques provides the unique opportunity to study the fluidized bed systems in great detail. Unfortunately, all techniques cannot be implemented in a single experiment. As a result, the same experiment is repeated as many times as necessary to collect the required data. The column is moved from one imaging system to the next and the experiment is repeated under the same operating conditions. It is believed that the data collected can be used as if all the data were collected during the same test. This paper presents preliminary experimental results for each set of experiments along with the nature and limitations of each set of experimental data. The results from each different system are combined in an effort to describe the complex hydrodynamics of the bed. The incremental information obtained in each set of experiments compared to the macroscopic measurements (flow rate and pressure drop) is demonstrated. Crown Copyright (C) 2001 Published by Elsevier Science B.V. All rights reserved.