The goal of the described project is to design mixtures of particles with optimal fluidization properties. Using high-throughput experimentation, a novel approach to study hydrodynamics in fluidized beds, the relevant properties can be obtained in a limited period of time. This approach is demonstrated by assessing the influence of particle size distribution on fluidized bed hydrodynamics of Geldart A powders. By manipulating the width of the particle size distribution of alumina powder, the bubble diameter is reduced up to 40%. The addition of fines to a given particle size distribution also decreases the bubble diameter up to 40%, whereas the addition of course particles hardly influences the bubble size. At low gas velocities, the dubble size was found to increase with fines addition or increasing standard deviation. (C) 2009 American Institute of Chemical Engineers AIChE J. 55: 2013-2023, 2009