Fluidization experiments were performed using several particle size distributions of spherical glass particles, ranging from Geldart B to D. An Electrical Capacitance Tomography (ECT) tomograph was utilized in the present study and its usefulness as a diagnostic tool is illustrated. During the experiments a 10.4 cm diameter column was utilized and the column was operated at atmospheric pressure and room temperature (cold fluidized bed). Statistical analyses were performed on the average solid fraction data obtained using the ECT tomograph. Using the time domain skewness and kurtosis the time series could be characterised and the quality of fluidization is determined at different superficial gas velocities (Azizpour, H., Sotudeh-Gharebagh, It, Zarghami, R., Abbasi, M., Mostoufi, N., Mahjoob, M., 2011. Characterization of gas-solid fluidized bed hydrodynamics by vibration signal analysis. International journal of Multiphase Flow, 37, 788-793). Statistical analysis is also used to characterise the influence of small particles on the bed hydrodynamics. (C) 2012 Elsevier Ltd. All rights reserved.